T4 vs SRF3 vs T2 vs FP pace at Buttonwillow Raceway Park
Quickest here:T4 1:58.339 Oscar Jackson, Cal Club 2025 qualifying · SRF3 1:50.233 Caleb Shrader, Cal Club 2025 qualifying · T2 1:51.198 Rylan Hazelton, Cal Club 2026 qualifying · FP 1:55.440 Michael Lewis, Cal Club 2025 race
T4SRF3T2FPsolid race · dashed qualifying · slower is lower
T4SRF3T2FPsolid race · dashed qualifying · each class's best lap as a share of T4's at the same event (the reference class, changeable above); 100% is level, higher is quicker
Event
T4
SRF3
T2
FP
Qual best
Race best
Trap
Qual best
Race best
Trap
vs T4
% of T4
Qual best
Race best
Trap
vs T4
% of T4
Qual best
Race best
Trap
vs T4
% of T4
Cal Club 2026 CALCL262026-02-21
2:01.678Izzy Sanchez · fastest of 5 · top 5 within 5.9s+3.339s (+2.82%)
2:01.157Izzy Sanchez · fastest of 5 · top 5 within 7.2s+1.235s (+1.03%)
135.5Izzy Sanchez+27.2 mph (+25.1%)
1:50.913Asad Nikadambaev · fastest of 27 · top 5 within 1.1s+0.680s (+0.62%)
1:52.070Asad Nikadambaev · fastest of 27 · top 5 within 0.8s+1.245s (+1.12%)
138.9Paul Marino+20.7 mph (+17.5%)
-9.087squal -10.765s
92.5%qual 91.2%
1:51.198Rylan Hazelton · fastest of 10 · top 5 within 2.5s-2.867s (-2.51%)
1:51.454Rylan Hazelton · fastest of 10 · top 5 within 3.0s-1.304s (-1.16%)
146.6Patrick Howe+32.2 mph (+28.1%)
-9.703squal -10.480s
92.0%qual 91.4%
1:58.084Steven Powers · fastest of 2+1.963s (+1.69%)
1:57.587Michael Lewis · fastest of 3 · top 3 within 2.1s+2.147s (+1.86%)
137.8Daniel Snow+26.9 mph (+24.3%)
-3.570squal -3.594s
97.1%qual 97.0%
84 rule changes (T4: 19, SRF3: 4, T2: 27, FP: 34)17 weight · 12 cars added · 10 induction · 6 engine · 6 suspension & brakes · 4 tyres & wheels · 2 aero · 1 removed · 24 wording · 2 other · FP class adds Toyota 5E DOHC 1497cc engine, 1900 lbs minimum weight, 23mm SIR induction. · FP Toyota 4E DOHC 1331cc engine added to Appendix N with 1900 lbs minimum weight. · FP Fiat X1/9 gains dual carburetor options with 28mm side-draft alternates and revised valve/transmission specs. · BMW 435i (2014-2017) added to T2 with 40mm restrictor, 3400 lbs minimum weight. · Nissan Z including Nismo added to T2 with 38mm restrictor, 3600 lbs base and 3650 lbs Nismo. · T2-T4 adjustable toe links now allow performance alternative bushings and spherical bearings, previously prohibited except in specified examples. · T2-TCR adds Link & Co 03 TCR and MG6 TCR, both 3000 lbs, 90% power, 275 max tire width. · Ford Mustang V6 (05-14) removed from T4 Spec Lines. · T4 Mustang 4.0 V6 tire size increases from 245 to 255. · T2-T4 adjustable toe links now allow performance alternative bushings and spherical bearings, previously prohibited except in specified examples. · T2, T3, T4 cars may relocate under-dash electronics and fuse boxes for access after roll cage installation. · T2 Cadillac CT4-V Blackwing minimum weight drops 50 lbs to 3750. · T2 C6 Corvette LS2 restrictor increases from 67mm to 80mm FPR. · T2 Dodge Viper SRT10 coupe weight reduced from 3675 lbs to 3650 lbs. · T2 Ford Mustang GT 5.0L 15-23 permits Ford Track/Performance Package aero parts M-16600-FP and M-16601-MPP. · T4 Performance now permits 1-piece alternative rotors matching spec line sizes; alternate brake kits allowed same. · T2, T3, T4 cars may relocate under-dash electronics and fuse boxes for access after roll cage installation. · T4 Performance now permits 1-piece alternative rotors matching spec line sizes; alternate brake kits allowed same. · EP Triumph TR2-TR4A allows 5-speed gearbox without overdrive; removes Weber carb and weight specification. · EP BMW Z3 2.5L restrictor reduced 52mm to 50mm, weight increased to 2550 lbs base; five other BMW models get smaller restrictors. · FP Lancia Scorpion minimum weight drops 80 lbs, to 1950. · FP Volkswagen Rabbit Convertible no longer required to remove factory roll bar. · FP Acura Integras and Honda Civics gain 50–79 lbs; Mazda Miata and Mercury Capri compression ratio to 11.0:1, valve lift to .425". · FP Honda B/D-series engines gain 105–120 lbs minimum weight across seven variants. · T2 Ford Mustang Boss 302 restrictor opens 56mm to 63mm; Mustang GT 5.0L 60mm to 65mm. · T2 Chevrolet Camaro SS/1LE (10-15) minimum weight reduced to 3575 lbs. · T2 Ford Mustang Challenge Dark Horse R (2024-) weight increases to 3825 lbs, displacement grows to 5038cc, tire width expands to 315. · Dodge/Plymouth Neon ACR SOHC/DOHC 95-99 newly classified T4 at 2350 lbs minimum weight. · EP Nissan 280Z minimum weight reduced from 2560 to 2400 lbs. · EP Mazda MX-5 1.8L 90-97 weight reduced to 2125 lbs from 2150 lbs. · HP Austin-Healey Sprite/Midget 1098cc minimum weight drops 80 lbs to 1550. · HP Volvo 142/142E gains compression ratio limit 12.0:1 and valve lift limit .425". · HP Mini Cooper 07-15 valve lift reduced to .390", from .450". · FP Scirocco 83-88 established as spec line with 1733–1803 lbs, 1715–1780 cc SOHC, 40/33 mm valves, Solex carbs or fuel injection. · FP and HP Volkswagen Rabbit descriptions updated: Convertible changed to Cabriolet in FP; Cabriolet added to three HP engine variants. · EP, FP, HP: rear drum brake to disc conversion clarified; rotors solid, diameter limited to largest front rotor permitted. · EP Ford Mustang (94-98) fuel injected throttle body inside diameter specified at 60. · FP Volkswagen Scirocco: remove two engine variants (1715cc and 1780cc), lighten one variant to 1663 lbs, allow 15×7 wheels instead of 13×7. · T3 and T4 Mazda MX-5 Miata models add approved gear kit PT#-0000-02-6100 to notes. · T4 Mazda MX-5 Miata/Club/RF (19-24) and (16-18) remove discontinued hardtop part #0000-07-5901; T3 MX-5 Miata (16-18) and Global Cup ND (16-21) same. · T2 Spec Corvette to 3200 lbs; Mustang 11-14 restrictor 60→62mm; Mustang 2015-23 tyre 295→315; 996 weights down to 3050/3000 lbs; 997.2 models restrictor 60→65mm, weights reduced 50 lbs. · T2 Spec Corvette rev limit set to 7100 rpm. · T4 Mini Cooper S R53 02-06 gear ratios changed to 12.79, 7.79, 5.65, 4.62, 3.83, 3.13 or 11.42, 7.18, 5.39, 4.40, 3.65, 2.96. · Chevrolet Cobalt SS Sport Coupe 06-10 reinstated to T4 with 2384cc engine, 2628 restrictor, 2700 lbs minimum weight. · Mercedes C230 Kompressor 2002-2005 classified in T4 at 3240 lbs with 17-inch wheels and 300/290 mm brakes. · T3 and T4 Mazda MX-5 Miata models add approved gear kit PT#-0000-02-6100 to notes. · T4 Mazda MX-5 Miata/Club 16-18 wheel size changed to 17 x 7.5 inches. · T4 Mazda MX-5 Miata/Club/RF (19-24) and (16-18) remove discontinued hardtop part #0000-07-5901; T3 MX-5 Miata (16-18) and Global Cup ND (16-21) same. · HP Plymouth Arrow transmission max speeds clarified to 4 or 5. · EP, FP, HP wheel diameter added to Appendix G as absolute maximum specification. · EP, FP, HP throttle body inside dimensions must remain stock with +/-.25mm tolerance; butterfly dimensions stock in FP, HP only. · SRF3 adds HD Oil Cooler P/N G1148500 as alternative to standard cooler P/N G480503. · SRF3 brakes restructured: Hawk Blue 801993 pads, Wilwood 800065 rotors only; adds Girling 880358, Wilwood 880357, Tilton 880360 master cylinders. · T2, T3, T4 Spec Lines table header changed from T2 to ET. · BMW M2 CS Cup 2020 must run Red power stick part #8324085, not Purple #8324089. · T2 Chevrolet Corvette C5 Z06 and C6 brake allowances clarified; stock calipers and rotors only for C5, specific sizes for C6. · T2 Chevrolet Corvette C5 LS1 restrictor reduced from 59mm to 58mm FPR. · T2, T3, T4 Spec Lines table header changed from T2 to ET. · EP BMW Z4 03-05 restricted to 52mm flat plate intake restrictor. · EP Fiat 124 Spider 1600 & 2000 weight drops 50 lbs to 2000; carburetors gain 2mm chokes to 36mm. · T4 now permits B-Spec and C-Spec cars to compete in the class. · HP Fiat X-1/9 base weights reduced 50–53 lbs across 1300 and 1500 spec lines. · T4 Ford Mustang V6 05-14 weight drops from 3400 to 3300 lbs. · T4 Scion FR-S and Subaru BRZ Solo Spec allow any 200TW 225/45/17 or 215/45/17 DOT tire. · T2 C6 Corvette LS2 restrictor increases from 63mm to 67mm FPR. · T2 Nissan 370Z max wheel size increases to 19 x 10.5 inches; mid link replacement for true coil overs now permitted. · T2 Cadillac CT4-V Blackwing maximum tire size increases from 295 to 315. · T4 Ford Mustang V6 05-14 allows GT 8.8 rear axle or 7.5 axle with 3.45:1 ratio. · T4 Ford Mustang V6 05-14 now permits OEM style rear deck spoiler similar to Laguna/CS packages. · Chevrolet Spark 16-22 classified HP Pre at 1850 lbs minimum weight, fuel injected, 1399 cc. · HP Ford Festiva 88-93 minimum weight drops to 1600 lbs, variants to 1640 and 1680 lbs; compression ratio raised to 11.0:1. · SRF drivers with disabilities may modify seat and controls for safety and comfort with approval and logbook notation. · SRF SADEV-SRF3 6-speed sequential transmission gear ratios wording clarified, effective 2025-04-01. · Ford Mustang Challenge Darkhorse R newly classified in T2 with 58 mm restrictor, 3775 lbs minimum weight. · T2 350Z (03-08) removes detailed OEM part numbers and consolidates permitted modifications into simplified allowance list. · EP BMW Z3 and 3-series models get smaller intake restrictors: Z3 2.5L to 52mm, Z3 2.8L to 55mm, 328i to 58mm, 325i to 56mm. · FP Acura Integra and Honda Civic models get smaller 51mm intake restrictors, down from 55mm; Del Sol VTEC weight increases to 2290–2405 lbs. · EP, FP, HP: interior or exterior mirrors meeting rule 9.3.36 now permitted. · EP Honda S2000 1997cc base loses 75 lbs to 2375; 2157cc base loses 60 lbs to 2450. · EP Mazda MX-5/Miata 99-05 minimum weight drops to 2100 lbs, 2153 lbs with power adder, 2205 lbs with two adders. · FP GTL Volkswagen Jetta Mark IV 4dr FWD 98.2 wheelbase newly classified. · FP Spec Lines option: carburettor chokes permitted as alternative to SIR, same size as listed SIR. · T2 BMW M2 CS Cup requires Red power stick #8324085 instead of Purple #8324089; Corvette C5 Z06 restrictor reduces to 58mm from 59mm.showhide
FP Request Toyota 5E Series Engines #38208cars addedneutralFP class adds Toyota 5E DOHC 1497cc engine, 1900 lbs minimum weight, 23mm SIR induction.
FP Request for Toyota 4E Series Engines #38209cars addedneutralFP Toyota 4E DOHC 1331cc engine added to Appendix N with 1900 lbs minimum weight.
FP Dual Carbs for the Fiat X1/9 #39593inductionunclearFP Fiat X1/9 gains dual carburetor options with 28mm side-draft alternates and revised valve/transmission specs.
T2 Request to Add 2014-2017 435i to T2 #38991cars addedneutralBMW 435i (2014-2017) added to T2 with 40mm restrictor, 3400 lbs minimum weight.
T2 Consideration for Nissan Z & NISMO Z to Touring 2 Class #39296cars addedneutralNissan Z including Nismo added to T2 with 38mm restrictor, 3600 lbs base and 3650 lbs Nismo.
T2 Allow Alt Bushing Material in Toe Links #39607suspension & brakesfasterT2-T4 adjustable toe links now allow performance alternative bushings and spherical bearings, previously prohibited except in specified examples.
T2 Request for Classification of MG6 TCR in T2-TCR Class #39702cars addedneutralT2-TCR adds Link & Co 03 TCR and MG6 TCR, both 3000 lbs, 90% power, 275 max tire width.
T4 T4 and T3 Feedback #39230removedneutralFord Mustang V6 (05-14) removed from T4 Spec Lines.
T4 T4 Mustang 4.0 #39489tyres & wheelsfasterT4 Mustang 4.0 V6 tire size increases from 245 to 255.
T4 Allow Alt Bushing Material in Toe Links #39607suspension & brakesfasterT2-T4 adjustable toe links now allow performance alternative bushings and spherical bearings, previously prohibited except in specified examples.
T2 Alternate Placement of Fuse Panel and Electronics Request #39370wordingneutralT2, T3, T4 cars may relocate under-dash electronics and fuse boxes for access after roll cage installation.
T2 Rebalance Blackwing Cadillac T2 for 2026 #39426weight -50 lbsfasterT2 Cadillac CT4-V Blackwing minimum weight drops 50 lbs to 3750.
T2 C6 LS2 Corvette Parity Request #39472inductionfasterT2 C6 Corvette LS2 restrictor increases from 67mm to 80mm FPR.
T2 T2 Tire Sizing #39490weight -25 lbsfasterT2 Dodge Viper SRT10 coupe weight reduced from 3675 lbs to 3650 lbs.
T2 Rear Spoiler for Mustang GT S550 (15-23) #39499aerounclearT2 Ford Mustang GT 5.0L 15-23 permits Ford Track/Performance Package aero parts M-16600-FP and M-16601-MPP.
T2 Clarify T4 Brake Rotor Allowance #39503suspension & brakesneutralT4 Performance now permits 1-piece alternative rotors matching spec line sizes; alternate brake kits allowed same.
T4 Alternate Placement of Fuse Panel and Electronics Request #39370wordingneutralT2, T3, T4 cars may relocate under-dash electronics and fuse boxes for access after roll cage installation.
T4 Clarify T4 Brake Rotor Allowance #39503suspension & brakesneutralT4 Performance now permits 1-piece alternative rotors matching spec line sizes; alternate brake kits allowed same.
FP TR2 Notes E&O #39180wordingunclearEP Triumph TR2-TR4A allows 5-speed gearbox without overdrive; removes Weber carb and weight specification.
FP Balance of Power #39187induction +50 lbsslowerEP BMW Z3 2.5L restrictor reduced 52mm to 50mm, weight increased to 2550 lbs base; five other BMW models get smaller restrictors.
FP Factory Roll Bar Removal on VW Convertible #39268wordingneutralFP Volkswagen Rabbit Convertible no longer required to remove factory roll bar.
FP FP Parity Request #39325weight +50 lbsslowerFP Acura Integras and Honda Civics gain 50–79 lbs; Mazda Miata and Mercury Capri compression ratio to 11.0:1, valve lift to .425".
FP Adjust former-GTL Honda's with B/D-Series Engines #39374weightslowerFP Honda B/D-series engines gain 105–120 lbs minimum weight across seven variants.
T2 Help the 2011-2014 s197Mustang GT and Boss302 Less Restriction #38523inductionfasterT2 Ford Mustang Boss 302 restrictor opens 56mm to 63mm; Mustang GT 5.0L 60mm to 65mm.
T2 Improving Competitiveness of Gen 5 Camaro SS #39021weight -50 lbsfasterT2 Chevrolet Camaro SS/1LE (10-15) minimum weight reduced to 3575 lbs.
T2 Adjust T2 Darkhorse R #39346weightslowerT2 Ford Mustang Challenge Dark Horse R (2024-) weight increases to 3825 lbs, displacement grows to 5038cc, tire width expands to 315.
FP HP Volvo 142 spec omission #38994engineslowerHP Volvo 142/142E gains compression ratio limit 12.0:1 and valve lift limit .425".
FP HP Mini DOHC 1.6 #38996engineslowerHP Mini Cooper 07-15 valve lift reduced to .390", from .450".
FP 83-88 FP Scirocco Spec Line Creation #38997cars addedneutralFP Scirocco 83-88 established as spec line with 1733–1803 lbs, 1715–1780 cc SOHC, 40/33 mm valves, Solex carbs or fuel injection.
FP Add to Rabbit description #39019wordingneutralFP and HP Volkswagen Rabbit descriptions updated: Convertible changed to Cabriolet in FP; Cabriolet added to three HP engine variants.
FP Clean-up 9.1.5.E.7e #39025wordingneutralEP, FP, HP: rear drum brake to disc conversion clarified; rotors solid, diameter limited to largest front rotor permitted.
FP Add TB size to Ford Mustang (94-98) Spec Line #39130wordingneutralEP Ford Mustang (94-98) fuel injected throttle body inside diameter specified at 60.
FP Correct Existing VW Scirocco Spec Line #39140enginefasterFP Volkswagen Scirocco: remove two engine variants (1715cc and 1780cc), lighten one variant to 1663 lbs, allow 15×7 wheels instead of 13×7.
T2 ND Gearset Request for T4 #39166wordingneutralT3 and T4 Mazda MX-5 Miata models add approved gear kit PT#-0000-02-6100 to notes.
T2 ND Spec Lines Wrong PT#'s #39170wordingneutralT4 Mazda MX-5 Miata/Club/RF (19-24) and (16-18) remove discontinued hardtop part #0000-07-5901; T3 MX-5 Miata (16-18) and Global Cup ND (16-21) same.
T2 Touring 2 Post-Runoffs BOP Adjustments and Changes #39274weight -50 lbsfasterT2 Spec Corvette to 3200 lbs; Mustang 11-14 restrictor 60→62mm; Mustang 2015-23 tyre 295→315; 996 weights down to 3050/3000 lbs; 997.2 models restrictor 60→65mm, weights reduced 50 lbs.
T2 Adjust rev limit on Spec Corvette in T2 #39282engineslowerT2 Spec Corvette rev limit set to 7100 rpm.
T4 02-06 Mini Cooper Gear Ratios #38966wordingunclearT4 Mini Cooper S R53 02-06 gear ratios changed to 12.79, 7.79, 5.65, 4.62, 3.83, 3.13 or 11.42, 7.18, 5.39, 4.40, 3.65, 2.96.
T4 Reinstatement of the 2005-2010 Cobalt into T4 #38987cars addedneutralChevrolet Cobalt SS Sport Coupe 06-10 reinstated to T4 with 2384cc engine, 2628 restrictor, 2700 lbs minimum weight.
T4 Request to Classify Mercedes C230K #39080cars addedneutralMercedes C230 Kompressor 2002-2005 classified in T4 at 3240 lbs with 17-inch wheels and 300/290 mm brakes.
T4 ND Gearset Request for T4 #39166wordingneutralT3 and T4 Mazda MX-5 Miata models add approved gear kit PT#-0000-02-6100 to notes.
T4 E&O wheel size on ND #39168tyres & wheelsunclearT4 Mazda MX-5 Miata/Club 16-18 wheel size changed to 17 x 7.5 inches.
T4 ND Spec Lines Wrong PT#'s #39170wordingneutralT4 Mazda MX-5 Miata/Club/RF (19-24) and (16-18) remove discontinued hardtop part #0000-07-5901; T3 MX-5 Miata (16-18) and Global Cup ND (16-21) same.
FP HP Plymouth Arrow spec omission #38995wordingneutralHP Plymouth Arrow transmission max speeds clarified to 4 or 5.
FP Add Wheel Diameter to Appendix G #39008wordingneutralEP, FP, HP wheel diameter added to Appendix G as absolute maximum specification.
FP Add TB ID tolerance to general Prod rules #39009wordingneutralEP, FP, HP throttle body inside dimensions must remain stock with +/-.25mm tolerance; butterfly dimensions stock in FP, HP only.
SRF3 Add HD Oil Cooler #38979otherneutralSRF3 adds HD Oil Cooler P/N G1148500 as alternative to standard cooler P/N G480503.
T2 Incorrect Touring Heading #38451wordingneutralT2, T3, T4 Spec Lines table header changed from T2 to ET.
T2 Clarifications needed to BMW M2 CS cup line #38536engineunclearBMW M2 CS Cup 2020 must run Red power stick part #8324085, not Purple #8324089.
T2 Fix brake allowance supersessions. #38554suspension & brakesslowerT2 Chevrolet Corvette C5 Z06 and C6 brake allowances clarified; stock calipers and rotors only for C5, specific sizes for C6.
T2 C5 Corvette correction #38782engineslowerT2 Chevrolet Corvette C5 LS1 restrictor reduced from 59mm to 58mm FPR.
T4 Incorrect Touring Heading #38451wordingneutralT2, T3, T4 Spec Lines table header changed from T2 to ET.
FP BMW Z4 update #38490inductionslowerEP BMW Z4 03-05 restricted to 52mm flat plate intake restrictor.
FP EP Fiat 124 Spider Competition Adjustment Request #38498weight -50 lbsfasterEP Fiat 124 Spider 1600 & 2000 weight drops 50 lbs to 2000; carburetors gain 2mm chokes to 36mm.
T4 Allow B-Spec cars to run in T4 #38439wordingneutralT4 now permits B-Spec and C-Spec cars to compete in the class.
FP Base Weight Adjustment for H-Production X1/9 Spec Lines #38255weight -50 lbsfasterHP Fiat X-1/9 base weights reduced 50–53 lbs across 1300 and 1500 spec lines.
T4 T4 Mustang #38059weight -100 lbsfasterT4 Ford Mustang V6 05-14 weight drops from 3400 to 3300 lbs.
T4 SSC tire allowance #38216tyres & wheelsneutralT4 Scion FR-S and Subaru BRZ Solo Spec allow any 200TW 225/45/17 or 215/45/17 DOT tire.
T2 C6 T-2 Corvette 6 Liter Engine Restrictor #37490inductionfasterT2 C6 Corvette LS2 restrictor increases from 63mm to 67mm FPR.
T2 370Z Mid link Replacement for True Coil Overs and OEM Wheel Size #38014suspension & brakesfasterT2 Nissan 370Z max wheel size increases to 19 x 10.5 inches; mid link replacement for true coil overs now permitted.
T2 T2 Cadillac tire #38210tyres & wheelsfasterT2 Cadillac CT4-V Blackwing maximum tire size increases from 295 to 315.
T4 Correct Ring and Pinion Ratio to T3, Sorry I Mean T4 3.7 V6 Stang #38041wordingneutralT4 Ford Mustang V6 05-14 allows GT 8.8 rear axle or 7.5 axle with 3.45:1 ratio.
T4 T4 Mustang #38058aeroneutralT4 Ford Mustang V6 05-14 now permits OEM style rear deck spoiler similar to Laguna/CS packages.
FP Request for Classification of Chevrolet Spark #37755cars addedneutralChevrolet Spark 16-22 classified HP Pre at 1850 lbs minimum weight, fuel injected, 1399 cc.
FP Request to Lower Ford Festiva Minimum Weight to 1600 LBS #37939weight -100 lbsfasterHP Ford Festiva 88-93 minimum weight drops to 1600 lbs, variants to 1640 and 1680 lbs; compression ratio raised to 11.0:1.
SRF3 Driver Safety & Comfort #37966wordingneutralSRF drivers with disabilities may modify seat and controls for safety and comfort with approval and logbook notation.
T2 Please class the Darkhorse R in T2 #37295cars addedneutralFord Mustang Challenge Darkhorse R newly classified in T2 with 58 mm restrictor, 3775 lbs minimum weight.
T2 T2 350Z Spec Line Cleanup #37603wordingneutralT2 350Z (03-08) removes detailed OEM part numbers and consolidates permitted modifications into simplified allowance list.
FP Request Competition Adjustment to BMW Z3 2.5L #37120inductionslowerEP BMW Z3 and 3-series models get smaller intake restrictors: Z3 2.5L to 52mm, Z3 2.8L to 55mm, 328i to 58mm, 325i to 56mm.
FP FP Class Adjustments #37458inductionslowerFP Acura Integra and Honda Civic models get smaller 51mm intake restrictors, down from 55mm; Del Sol VTEC weight increases to 2290–2405 lbs.
FP Interpretation of Production Rules on Mirrors #37235wordingneutralEP, FP, HP: interior or exterior mirrors meeting rule 9.3.36 now permitted.
FP Weight Reduction for Honda S2000 #37466weightfasterEP Honda S2000 1997cc base loses 75 lbs to 2375; 2157cc base loses 60 lbs to 2450.
FP Mazda 1999 Miata 1.8L #37488weight -50 lbsfasterEP Mazda MX-5/Miata 99-05 minimum weight drops to 2100 lbs, 2153 lbs with power adder, 2205 lbs with two adders.
FP Errors & Omissions #37648cars addedneutralFP GTL Volkswagen Jetta Mark IV 4dr FWD 98.2 wheelbase newly classified.
FP GTL/FP consolidation 2025 Rules #37659inductionneutralFP Spec Lines option: carburettor chokes permitted as alternative to SIR, same size as listed SIR.
T2 T2 BOP #37312otherslowerT2 BMW M2 CS Cup requires Red power stick #8324085 instead of Purple #8324089; Corvette C5 Z06 restrictor reduces to 58mm from 59mm.
Cal Club 2025 CALCL252025-02-22
1:58.339Oscar Jackson · fastest of 5 · top 5 within 8.3s
1:59.922Oscar Jackson · fastest of 4 · top 4 within 7.3s
108.4Tony Kiratsous
1:50.233Caleb Shrader · fastest of 33 · top 5 within 0.4s
1:50.825Caleb Shrader · fastest of 32 · top 5 within 0.8s
118.2John Black
-9.097squal -8.106s
92.4%qual 93.2%
1:54.065Oli Thordarson · fastest of 2
1:52.758Oli Thordarson · fastest of 2
114.4Oli Thordarson
-7.164squal -4.274s
94.0%qual 96.4%
1:56.121Michael Lewis · fastest of 5 · top 5 within 25.2s
1:55.440Michael Lewis · fastest of 6 · top 5 within 10.7s
110.9Michael Lewis
-4.482squal -2.218s
96.3%qual 98.1%
469 earlier rule changes on record, in force before Cal Club 2025 (from 2019)78 cars added · 78 weight · 53 suspension & brakes · 27 tyres & wheels · 22 induction · 14 aero · 13 engine · 3 removed · 164 wording · 17 other · EP BMW Z3 2.5L requires 52mm flat plate intake restrictor; Z3 2.8L 55mm; 328i/is E36 58mm; 328i/ci E46 58mm; 325i/is E46 56mm; 325i/is E36 56mm; 325is M-Technic 56mm. · T2 Mustang GT 5.0L combines 2015-17 and 2018-23 with different restrictors: 63mm for Gen 2, 60mm for Gen 3. · T2 Chevrolet Camaro 1LE gains 100 lbs to 3600, restrictor increases to 62mm FPR. · T2 BMW M235iR (-2016) now permits oil cooler, radiator per touring rules, and silicone charge pipe. · Ford SCCA Club Spec Mustang classified T3 at 3350 lbs with driver; Mazda SCCA Club Spec MX-5 classified T4 at 2500 lbs with driver. · T4 Ford Mustang V6 (05-14) final drive set to 3.45, GT/CS front bumper cover permitted with front fascia. · Ford SCCA Club Spec Mustang classified T3 at 3350 lbs with driver; Mazda SCCA Club Spec MX-5 classified T4 at 2500 lbs with driver. · EP BMW 325i/is E30 (84-91) weight reduced 50–52 lbs across three spec lines to 2150, 2204, 2258. · FP Spridget and Midget 1275cc and 1500cc spec line corrections to bore, stroke, displacement, and valve sizes. · F Production now allows GT-Lite cars meeting Appendix N specifications to compete, effective 2025-01-01. · T2, T3, T4 remove nine, nine, and thirty-six expired spec lines respectively, effective 2025-01-01. · T2 Ford Mustang GT 5.0L (11-14) weight reduced from 3575 to 3525 lbs. · T2 Spec Corvette clarifies braking, tires, cooling, suspension, and Spec+ upgrades; SC-3200, SC+-3300 lbs. · T2, T3, T4 remove nine, nine, and thirty-six expired spec lines respectively, effective 2025-01-01. · T4 2016-2018 Mazda Miata MX-5 minimum weight reduced to 2575 lbs from 2650 lbs. · T2 and T3 Mustang spec lines remove redundant driveshaft alternate/aluminum allowance wording. · T2 Chevrolet Corvette C6 LS3 restrictor increases from 53mm to 56mm flat plate. · T2, T3, T4 fuel cell installations may remove charcoal canisters, emissions valves, and sensors. · T2, T3, T4 brake component wording clarified: 2-piece rotors allowed in T2 within 5% OE diameter, T3 within 2% OEM diameter. · T2, T3, T4 fuel cell cars may remove charcoal canisters, emissions valves, and sensors. · Porsche Spec Boxster moves to T4, minimum weight 2750 lbs, requires 3 Super Tour events before Runoffs eligibility. · T2 Chevrolet Corvette C6 Coupe/Grand Sport wheels widened to 18×11 or 19×13. · T4 BMW 320i 14-15 Spec Line expires 12/31/24 removed; Turner Motorsports intercooler #024703TMS02 allowed. · Cadillac CTS 02-07 3.6L classified in T3. · T2 Corvette C5 Z06 restrictor split by engine: LS1 59mm, LS2 63mm, LS3 56mm FPR. · T2 Chevrolet Corvette Z06 (06-12) Spec Line deleted entirely. · T2 and T3 Mustang spec lines remove redundant driveshaft alternate/aluminum allowance wording. · T4 Mini Cooper S R53 now allows Alta 15% Pulley #AMPENG20X. · T4 removes restriction on aftermarket wheel weight minimum of 15 lbs. · T2, T3, T4 fuel cell installations may remove charcoal canisters, emissions valves, and sensors. · Mazda 3 (19-24) newly classified in T4 at 2850 lbs with 17×8 wheels and 245 tires. · T2, T3, T4 brake component wording clarified: 2-piece rotors allowed in T2 within 5% OE diameter, T3 within 2% OEM diameter. · T2, T3, T4 fuel cell cars may remove charcoal canisters, emissions valves, and sensors. · T3 and T4 Mazda RX-8 and MX-5 permit transmission kit #0000-02-5700. · Porsche Spec Boxster moves to T4, minimum weight 2750 lbs, requires 3 Super Tour events before Runoffs eligibility. · Ford Mustang V6 (05-14) newly classified to T4 with 50mm restrictor, 3400 lbs minimum weight. · T4 BMW 320i 14-15 Spec Line expires 12/31/24 removed; Turner Motorsports intercooler #024703TMS02 allowed. · Unable to summarize: rule changes specified in letter #37281, not provided. · Cadillac CTS 02-07 3.6L classified in T3. · T4 Honda Civic Si 06-11 minimum weight drops 50 lbs to 2900, restrictor clarified. · T4 NC MX-5 06-15 removes SM5 suspension allowance, clarifies Mazda Motorsports LSD part number, adds weight penalty for other LSDs. · T4 Mazda MX-5 Miata/Club (16-18) wheel size changes to 17 x 7.5 inches. · T4 Mazda RX-8 gets 59mm restrictor and 3200 lbs; MX-5 Club drops to 2550 lbs. · T4 Mazda MX5 Miata/Club/RF 19-24 wheel size changes to 17 x 7.5. · HP Sprite and Midget 1275cc and 1098cc Level 2 compression ratio raised to 12.0:1. · T2 Spec Corvette now allows 295 R compound DOT tires as alternative to Nankang NS-2R. · T4 Honda Civic Si 06-11 permitted to use LSD per category rules. · FP Honda CRX/CRX Si 84-87 block material changes from Iron to Alum. · SRF3 air filter rule removes K&N RC-9160 option, leaving only P/N WM301020 allowed. · SRF brake rotor minimum thickness increases from 12.20mm to 13.25mm, Wilwood vented rotor P/N 800065. · SRF3 Hoosier logo placement changes from four decals to three decals in different locations. · SRF Hoosier decal requirement reduced from four decals in specific locations to three decals with simpler placement rules. · HP Volkswagen Golf and Jetta 85-92 track correction: front 1537mm (60.5in), rear 1529mm (60.2in). · SRF wet tires: P185/60R13 H20/W2 option removed; P185/65R13 W2 front now required with P205/60R13 W2 rear. · T2 Corvette C6 LS2 restrictor increases to 63mm; Camaro 1LE weight drops to 3500 lbs, restrictor tightens to 58mm FRP. · T2 Subaru Impreza WRX STi (03-07) and (08-11) expiration notes removed. · T2 Ford Mustang 5.0L gets 100 lb weight reduction with 4-piston Brembo brakes and 355mm rotors; EcoBoost brake note removed. · T4 Chevrolet Camaro V-6 (96-02) weight reduced from 3250 lbs to 3150 lbs. · T4 Mazda MX-5 Miata/Club 16-18 drops 50 lbs to 2650; 19-24 RF drops 50 lbs to 2750. · Ford Mustang GT 5.0L and V6 now permit Track/Performance Package parts in T2 and T3. · T2 Ford Mustang S550 5.0 Gen2/Gen3 gains 100 lbs with stock or Brembo 355mm brakes. · T2-T4 Ford Mustangs: remove 25 lbs penalty for non-OEM driveshaft, clarify alternate driveshaft allowances. · T2 Corvette C5, Camaro SS, Firebird, Solstice GXP, C6 allow four or six piston front calipers. · Audi S4 (2000-2002) moves to T3 with 3400 lbs minimum weight, 38mm turbo inlet restrictor required. · Ford Mustang GT 5.0L and V6 now permit Track/Performance Package parts in T2 and T3. · Mercedes C300 4Matic 2008-2011 homologated to T4 at 3,725 lbs with 18x8.5 wheels, 245 max tires, 3.27 final drive. · T2-T4 Ford Mustangs: remove 25 lbs penalty for non-OEM driveshaft, clarify alternate driveshaft allowances. · T4 Mini Cooper S (02-04) deleted; (05-06) model year corrected to R53; (07-13) R56 simplified specs; (2014-2023) added with spring rates. · T4 OEM intake chambers, resonators and acoustic devices may be removed if ports sealed and before restrictor. · Audi S4 (2000-2002) moves to T3 with 3400 lbs minimum weight, 38mm turbo inlet restrictor required. · Nissan 300ZX 84-89 classified to EP at 2550 lbs minimum, 2960cc 6-cyl SOHC, fuel injection, 12.0:1 compression limit, 0.500" valve lift limit. · Mazda RX-7 92-97 newly classified EP Prep Level 2 at 2200–2310 lbs with 13B 6-port rotary engine. · EP Mazda RX-8 (04-11) alternate spec line removed; one primary line remains. · SRF3 alternator pulley minimum weight reduced from 12 oz to 11 oz. · T4 Mazda MX-5 Club 06-15 now permits OEM front spoiler NF51-V4-900F. · T4 Ford Mustang V6 (05-10) weight reduced 50 lbs to 3225. · T4 Mini Cooper S 02-04 and 05-06 now allow Milltek exhaust manifold #SSXM459 and 25mm rear sway bar. · FP Honda CRX 84-87 can replace plastic front header, rocker skirt, door cap panels with stock-appearance replicas in alternate materials. · FP Acura Integra and Honda Civic models now require 55mm Flat Plate Intake Restrictor. · T3 and T4 Mazda RX-8 may remove or disable factory oil injection system. · T2 BMW M3 01-06 max wheel size increases from 18 x 9 to 18 x 10 inch. · T2, T3, T4 driveshafts may use alternative materials or one-piece units; non-OEM adds 25 lbs. · T3 and T4 Mazda RX-8 may remove or disable factory oil injection system. · T4 Mazda MX5 Miata/Club/RF year range extended to 2024, suspension package permitted with 100 lbs weight increase. · T4 Volkswagen Rabbit 2.5 (06-09) front brakes increase from 228 to 288 vented disc. · T2, T3, T4 driveshafts may use alternative materials or one-piece units; non-OEM adds 25 lbs. · T4 Mazda MX-5 Miata/Club 16-18 removes differential stock requirement, allows up to 500lb front and 300lb rear springs. · T2 Porsche Cayman S 06-09 allows StopTech ST60/ST40 brake kit with 50 lb penalty. · T4 Mazda RX-8 allows Mazdaspeed radiator, coil spring kit, OE rear spoiler, front air dam, springs to 700 lb front/400 lb rear, oil metering pump bypass, sway bars to 32 mm front/19 mm rear. · HP removes four redundant VW spec lines: Rabbit Cabriolet 1780, Scirocco 1588, Scirocco 1780 8-valve, Scirocco 1588. · FP Mazda Protégé ES (01-03) model designation updated to include /5 variant. · T2-T4 Spec Lines remove wheelbase requirement, replace with Required Restrictor specification. · T2 and T3 Nissan 370Z brake rotors enlarged: front 320x28 to 355x32mm, rear 320x16 to 350x20mm vented. · T2 Mustang GT 5.0L 2018+ now permits BMR rear upper control arm camber links part #UTCA064. · T2-T4 Spec Lines remove wheelbase requirement, replace with Required Restrictor specification. · T4 Mazda RX-8 rear spring opens to any 400lb, was specific part numbers only. · T2 and T3 Nissan 370Z brake rotors enlarged: front 320x28 to 355x32mm, rear 320x16 to 350x20mm vented. · HP Honda Civic 1.5 (88-91) weight reduced to 2175 lbs base, 2229 lbs with power adder, 2284 lbs with two. · T2 Mustang GT 5.0L 15-17 now permits BMR rear upper control arm camber links part #UTCA064. · T2 Chevrolet Camaro SS, 1LE, Corvette C5/C6, Z06, and Pontiac Firebird, Solstice GXP now allow four or six piston front calipers. · T2 Cadillac CT4-V Blackwing Runoffs qualification requirement removed. · T2, T3, T4 battery replacement wording simplified; OEM weight tolerance requirement removed. · T4 now permits C-Spec cars to compete alongside B-Spec cars. · T2-T4 spec lines for 46 cars expire 12/31/24; appeal required to continue. · T2 Chevrolet Camaro 1LE minimum weight increases to 3575 lbs, restrictor plate widens to 60mm. · T2, T3, T4 battery replacement wording simplified; OEM weight tolerance requirement removed. · T4 Mazda MX-5 Miata/Club (16-18) and (19-21) permitted to replace 3rd and 4th gears with specific parts. · T4 now permits C-Spec cars to compete alongside B-Spec cars. · T2-T4 spec lines for 46 cars expire 12/31/24; appeal required to continue. · FP Acura Integra LS and Honda Del Sol VTEC minimum weights increase 25–78 lbs across all configurations. · EP BMW Z3 2.5L weight increases to 2500 lbs, 2563 lbs with turbo, 2625 lbs with supercharger. · FP Honda throttle body specs corrected: Civic 1.5 to 42", Si to 55", CRX variants adjusted. · EP Mazda MX-5 1.8L 1990-97 minimum weight drops to 2150 lbs; 1994-97 variants to 2000, 2050, 2100 lbs respectively. · EP Triumph GT6 dual 1.75" carbs weight drops to 1940 lbs; triple Weber 40 DCOE options consolidated. · EP Honda S2000 fuel injected throttle body inside diameter increases from 62mm to 64mm. · EP Triumph TR8 dry sump allowance moved from carburetor line to notes section. · EP Porsche 944/924S 2.5L and 2.7L weight minimums corrected: 2479cc to 2306/2363 lbs, 2681cc to 2358/2415 lbs. · SRF rain/brake light now requires Super Bright LEDs Inc. P/N PT-STRB-R24 with specific connector and rain light switch. · SRF requires Super Bright LEDs P/N PT-STRB-R24 rain/brake light with strobing capability and specific wiring. · SRF adds brake duct and pedal extension rules, rear shift cable clamp option, camber limit to 5.0°, radiator opening height 3.5" ±0.5", and P2 engine restrictor changes. · T2 Cadillac CT4-V Blackwing rear wheels widen from 18 x 10 to 18 x 11. · T2 BMW M2 CS Cup drops 50 lbs to 3550; M235iR drops 50 lbs to 3300. · T2 Spec Corvette minimum weight drops 175 lbs to 3200, tire rules tighten to Nankang NS-2R only. · T2 Dodge Viper SRT-10 rear tyre narrowed from 345/30 to 335/30. · T2 Ford Mustang GT 5.0L three generations gain 50-75 lbs minimum weight; restrictors increase to 58-60mm. · T2 Chevrolet Camaro 1LE minimum weight drops 50 lbs to 3500, restrictor opens to 58mm flat plate. · T2 C5 Z06 removes restrictor note from weight; C5/C6 Corvettes increase restrictors to 59mm, 63mm LS2, 53mm LS3. · T3 Nissan 370Z model years expanded to include NISMO Edition through 2022. · T4 Mazda MX-5 ND1 minimum weight increases 50 lbs to 2700; suspension springs now allow up to 500 lb front, 300 lb rear. · T4 BRZ/FRS/86 spring allowance clarified: 225 lb front and 300 lb rear springs permitted; non-OEM LSD allowed with +50 lbs penalty. · T4 Acura TSX 2004-2008 now allows header. · T3 Nissan 370Z model years expanded to include NISMO Edition through 2022. · EP Porsche 944/924S combines 2.5L and 2.7L variants with new weights: 2250–2415 lbs depending on engine and year. · FP Toyota Corolla 2TC loses 43 lbs to 1810; HP Corolla loses 50–52 lbs to 1910–2006. · EP Triumph GT6 minimum weight reduced to 1800 lbs. · T2 BMW M2 CS Cup 2020- permitted to add hood vents conforming to 9.1.9.2.D.8.a.7. · SRF radiator rule clarified: P/N 480466 replaceable with Automotive P/N 1R698, CU698 or manufacturer equivalent with documentation. · T4 Mercedes Benz CLK 320 Coupe model years expand to 2000-2007, C320 Sedan added. · T2 Chevrolet Corvette C6 LS2 restrictor plate increases from 58mm to 60mm flat plate. · T2 Cadillac CT4-V Blackwing permitted to use Radium fuel surge tank behind fireproof bulkhead. · T3 Mazda RX-8 removes transmission/final drive pairing requirement; T4 removes same requirement, adds Mazdaspeed radiator and coil spring kit. · T3 BMW 320i (14-15) gains aftermarket intercooler permission; T4 loses it. · T3 Pontiac Solstice GXP minimum ride height set to 3 inches. · T3 Mazda RX-8 removes transmission/final drive pairing requirement; T4 removes same requirement, adds Mazdaspeed radiator and coil spring kit. · T3 BMW 320i (14-15) gains aftermarket intercooler permission; T4 loses it. · T3 Pontiac Solstice GXP minimum ride height set to 3 inches. · FP and HP Sprite, Midget, and Spitfire 1500 intake valve size corrected to 36.6/(1.44). · HP Volkswagen Rabbit Cabriolet 1780 removed; Rabbit 1588 and 1715 reclassified with engine sizes and year ranges specified. · T2 Nissan 370Z allows NISMO suspension alternatives to SPL parts; rear toe arms removed from permitted list. · T4 Mini Cooper S R53 loses 50 lbs, to 2700 for both 02-04 and 05-06 model years. · Ford Fiesta HP and Chevrolet Sonic FP model year ranges extended from 2016 to 2019. · SRF Hoosier wet front tire updated to P/N 46100 P185/60R13 H20 or W2. · T2 Porsche Cayman S model year range extended from 06-08 to 06-09. · T4 Mini Cooper S all years now run 17-inch wheels, up from 16, with wider rims to 8 inches. · T4 Volkswagen Rabbit 2.5 (06-09) consolidates 06-07 and 08-09 models; Integrated Engineering intake allowed with 25lb penalty. · T4 Audi A4 2.8 V6 wheels grow to 17x8, tyres to 245, springs now 800lb with 32mm sway bars. · 1978-80 Toyota Celica classified FP Prep Level 2, 2100-2205 lbs, 2190cc SOHC, 11.0:1 compression, .450" valve lift max. · SRF Hoosier front rain tyre part number changes from 46100 to 46101 P185/65R13 W2. · T2 Chevrolet Corvette C5 Z06 restrictor increases from 53mm to 56mm; 58mm option removed. · T2 upper and lower control arm bushings can now use polyurethane, delrin, or alternate synthetic materials. · T2 Cadillac CT4-V Blackwing now permits adjustable sway bar end links. · Acura TSX 2004-2008 newly classified in T4 at 3000 lbs minimum weight with 2354cc engine. · T4 Mustang rear sway bar increases from 22mm to 28mm permitted. · SRF Renault Alliance solid front rotors banned; restrictor reduced 35mm to 34mm for 2011+ Kawasaki; minimum weight increased to 1100 lbs for 2009+ stock engines. · SRF3 tail sections allowed on SRFs with GEN3 airbox shimming up to 19 mm; alternate dash panel P/N 180100 or 180101 relocated in rules. · T2 Honda Civic Type-R tire size increases from 275 to 295. · T3 BMW 320I now permitted to use aftermarket intercooler. · FP Mazda Protégé ES (01-03) renamed to include P5 designation as Mazda Protégé ES/5 (01-03). · T2 C5 Corvette permitted GM Motorsports T1 suspension package and SpecCorvette SCT-1 swaybars. · T2/T3 Mustang GT 5.0L and V6 (11-14) may remove upper grille fog lights, replace with mesh or screen. · T4 Mazda MX-5 ND2 (19-21) classified: 1998cc, 2309mm wheelbase, 225 max tires, 2800 lbs. · T2/T3 Mustang GT 5.0L and V6 (11-14) may remove upper grille fog lights, replace with mesh or screen. · T4 Mazda MX-5 Club Model 06-15 Mazda Motorsports LSD part number corrected from 32655 to 0000-02-5564. · EP, FP, HP cylinder head ports limited to 1 inch maximum depth matching from mating surface. · T2 BMW M235iR weight reduced 50 lbs to 3350, aftermarket shocks now allowed. · T5 class added as regional-only; T5 tyres maximum width 225, minimum aspect ratio 45. · T2-T5 Touring front and rear suspension maximum negative camber changed to 3.5 degrees. · T4 Honda Civic Si 06-11 now permits 32mm sway bars front and rear and 700 pound springs. · T5 class added as regional-only; T5 tyres maximum width 225, minimum aspect ratio 45. · T2-T5 Touring front and rear suspension maximum negative camber changed to 3.5 degrees. · T2 Dodge Viper SRT-10 wheel size 18x11 rear, weight to 3675 lbs, throttle restrictor hole 44mm convertible or 42mm hardtop. · T4 Ford Mustang V6 (05-10) wheels widen to 18x9, front brakes grow to 314mm vented, weight drops to 3275 lbs. · T4 Mazda MX-5 Club (06-15) minimum weight drops 25 lbs to 2600; Mazda LSD #32655 now permitted without penalty. · T3 Subaru BRZ 2022- minimum weight up to 2975 lbs; spring rate to 1000 F/R, brake parts allowed without penalty. · VW New Beetle 2.5L 5-cyl added to EP at 2400–2520 lbs, 2480 cc, fuel injection, comp ratio 12.0:1 max, valve lift 0.500" max. · EP Mazda RX-7 12A/13B gains fuel injection option on dual-y manifold with 42mm choke(s). · EP VW Corrado 92-95 stroke corrected to 90.3 mm, displacement to 2792 cc. · T4 Mazda3 04-09 now permits Corksport balance shaft delete kit GEN-6-504-10. · EP Subaru BRZ and Toyota 86/Scion FR-S model year ranges updated to 13-20. · SRF tire rule wording changed from 'Tires: must be run as delivered' to 'Tires must be run as delivered.' · SRF brake rotor minimum thickness reduced from 13.25 to 12.20mm; seal and air filter rules clarified. · T2 BMW M235iR/M240iR: 240iR/Evo package now permitted without 50 lb penalty; Evo package clarified to 75 lbs. · T2 BMW E92 M3 (08-14) permitted to use Fall Line Suspension arms from G8X/F8x/E9x M3, E9x M3/E82 1M. · T4 Hyundai Tiburon V-6 wheel width increases from 7 to 8 inches at 17-inch diameter. · FP Lotus Super Seven 91.7 ci minimum weight increases to 1580 lbs. · EP Mazda MX-5 Global Cup 16-22 minimum weight set to 2400 lbs; sequential gearbox allowed with +150 lbs penalty. · BMW 128i (08-13) classified in EP at 2700 lbs minimum with stock throttle body, 11.0:1 compression ratio, 0.400 in. valve lift limits. · EP/FP/HP open cars may now use carbon fiber hardtops if they retain OEM appearance in all exterior profiles. · Mazda Protégé ES 99-00 classified in FP at 2150–2258 lbs with 1839cc DOHC engine, fuel injection, 11.0:1 compression, .450" valve lift limit. · T2-T4 Touring cars with alternative springs may use performance top hats with spherical bearings on shocks and struts. · T2 BMW E92 M3 (08-14) note reference changed from 77 to 78. · Cadillac CT4-V Blackwing (2022+) classified in T2 at 3800 lbs with 94 x 85.6mm engine. · T4 Mazda3 i 2.0L added as spec line with 1999cc displacement and 2425 lbs minimum weight. · T2-T4 Touring cars with alternative springs may use performance top hats with spherical bearings on shocks and struts. · EP Mazda RX-8 13B carburetor rules clarified: dual 2bbl carb, fuel injected throttle body, or stock fuel injection permitted. · EP and FP Production clarifies idle control valve rules: stock devices allowed original, removed with blocked ports, or mechanical replaced with electronic stock type. · FP BMW 325e/es displacement corrected from 1647 to 2693 cc. · T2-T4 cars model year 2018+ may use non-OEM ECU with 75 lb weight penalty via spec line adjustment. · BMW M2 CS Cup 2020- now permits specific exhaust part #18302459928 and hot country package cooling parts. · 2022+ Cadillac CT4-V Blackwing classified in T2 at 3564cc, 3800 lbs, 18×10/11 wheels, 295 MT tires. · T2-T4 cars model year 2018+ may use non-OEM ECU with 75 lb weight penalty via spec line adjustment. · T4 Nissan Sentra SE-R Spec V 02-06 now permits balance shaft removal kit OQR25-NOBAL. · T4 BMW 323 (98-00) wheelbase increases to 2725 mm, final drive ratio changes to 3.07. · T4 Mazda RX-8 04-12 gains Eibach spring alternatives to Mazda Motorsports springs front and rear. · T4 Mazda3 04-09 tire size increases from 235 to 245. · T4 Ford Mustang V6 05-10 shock part numbers corrected to 8741-1494SPORT front and 8241-1240SPORT rear. · T4 Scion FR-S and Subaru BRZ Solo Spec Coupes updated to 2020 specifications Rev 7/20. · T4 2016–18 Mazda MX-5 Miata/Club gains 100 lbs. for approved suspension package with specific springs. · EP BMW Z3 2.5L intake restrictor reduced from 59mm to 58mm flat plate. · Ford Mustang 99-03 classified to EP at 2700/2768/2835 lbs; 94-98 Mustang weight reduced to 2550/2614/2678 lbs. · EP, FP, HP Improved Touring cars may use any DOT-approved tire per section 9.3.45 in Production class. · FP VW Golf III/Jetta III 93-98 intake valve to 39.5/1.56, exhaust to 32.9/1.30. · T2-T4 grill openings may remove non-metallic webbed false sections; 16 square inch limit removed. · T2 Chevrolet Corvette C6 LS2 restrictor increases from 56mm to 58mm. · T2-T4 grill openings may remove non-metallic webbed false sections; 16 square inch limit removed. · T3 Spec Lines Subaru BRZ TS (13-21) added to class specification wording. · EP, FP, HP classes allow stock/original idle control devices unmodified or completely removed with openings blocked. · T2 BMW Z4M 06-08 weight reduced from 3150 to 3100 lbs. · T4 Mazda MX-5 Club 06-15 allows non-OEM LSD with +50 lbs penalty; removes stock transmission and differential requirements. · T4 2005-2010 Ford Mustang V6 now specifies Koni damper part numbers 8741.1494 front and 8741.1240 rear. · EP Porsche 968 intake valve size increased from 37 to 39.0 mm. · EP, FP, HP front-wheel-drive cars may alter body and suspension to install alternate transmission, transaxle, and axle shaft. · EP BMW Z3 2.5L allows alternate throttle body from 92-95 325i with Turner adapter; head casting 1738400 permitted with specific blocks. · FP Honda Civic Del Sol VTEC removes restrictions on dry sump, connecting rods, intake manifold porting, crankshaft, rocker arms, cam followers. · FP Honda Prelude 84-87 and Mazda GLC/323 86-88 standardize valve lift measurement and remove Level 1 dry sump restrictions. · T2 Dodge Viper SRT-10 loses 50 lbs to 3550; throttle restrictor hole shrinks from 43mm to 41mm. · T2-T4 clarified: grill opening area may increase max 16 sq in for radiator cooling only, retaining factory mesh shape. · T2, T3, T4 radiator and coolant hoses may be replaced with aftermarket options; coolant temp sensor modification permitted. · T2, T3, T4 clarify that spec lines listing permitted or allowed parts are alternatives to category rules, not replacements. · T2 Spec Mustang model designation changed to Ford Spec Mustang. · T2-T4 clarified: grill opening area may increase max 16 sq in for radiator cooling only, retaining factory mesh shape. · T4 BMW 323 98-00 minimum weight drops to 3250 lbs, 50mm restrictor removed. · T4 Honda Civic Si consolidates 12-13 and 14-15 into single 12-15 spec line with updated suspension allowances. · T2, T3, T4 radiator and coolant hoses may be replaced with aftermarket options; coolant temp sensor modification permitted. · T2, T3, T4 clarify that spec lines listing permitted or allowed parts are alternatives to category rules, not replacements. · T4 Acura RSX/RSX Type-S 02-06 removes requirement that original wheels must remain stock. · T4 Chevrolet Camaro V-6 (96-02) removes requirement that shock/struts, mounts, and transmission differential remain stock. · EP Porsche 944S2 89-91 requires 56mm flat plate intake restrictor; comp ratio max 12.0:1, valve lift max 0.500". · HP Corolla GTS RWD (84-87) added at 2300 lbs; HP Corolla FX16 FWD (87-88) added at 2260 lbs; old Corolla (84-87) removed. · SRF front wet tire changes from P185/60R13 H20 to P185/65R13 W2; SRF3 adds mandatory G301048 restrictor plate Jan. 1, 2022. · T2 BMW M2 CS Cup 2020 rear brake rotor reduced from 390 mm to 380 mm. · Nissan Sentra SE-R Spec V (2007–2012) newly classified in T4 at 3000 lbs minimum weight. · T4 Mazda RX-8 04-12 allows alternate sway bars max 32mm front, 19mm rear; removes 60mm restrictor requirement. · T4 BMW 320i (14-15) now allows GFB T9357 aluminum diverter valve. · T4 Honda Civic FWD gets wider 8-inch wheels, 245 tyres max, and sway bar allowances to 29mm front, 22mm rear. · T4 multiple cars: Volkswagen Rabbit 2.5 (08-09) to 2675 lbs; Mazda MX-5/Club (06-15) to 2625 lbs; RX-8 to 3125 lbs; Honda/Acura/Chevy/Mazda wheel widths 7 to 8 inches. · T4 Volkswagen Passat, Jetta 1.8T adds 2014 model year to eligible years. · BMW M2 (2017+) added to T2 with 2979cc engine, 10.5x18 wheels, 295 tires, 3650 lbs weight. · Porsche 911 997.2 GTS (09-12) classified in T2 at 3400 lbs with 60mm flat plate restrictor required. · T4 Volkswagen Passat, Jetta 1.8T adds 2014 model year to eligible years. · HP Toyota MR-2 1.6L (85-89) track corrected to 15.47 inches front and rear. · T2 BMW M2 CS Cup 2020- must run Purple power stick, part #8324089 instead of #TBD. · Honda S2000 (00-03) reclassified as EP Prep with F22c engine option: 1997cc or 2157cc, weight 2450–2636 lbs depending on displacement. · EP Nissan 240-SX S13/S14 loses 200-210 lbs minimum weight; comp ratio rises to 12.0:1, valve lift to .500. · SRF wet tyres add Hoosier P185/60R13 W2 front and P205/60R13 W2 rear as alternatives to H20. · SRF adds SADEV-SRF3 6-speed sequential option with final drive 3.20 versus OEM 5-speed 3.85. · SRF seal procedures clarified: unsealed components need CSR inspection and logbook notation instead of engine removal. · T2 Porsche 911/997.1 (06-08) now allows alternate Cargraphics CARP97DFIFKR exhaust manifold. · EP Lotus/Caterham 7 America carburetor changed from IT fuel injection prep to fuel injection. · Plymouth Arrow 1598cc four-cylinder classified to HP at 1800 lbs minimum weight. · BMW 318i E30 (84-85) reclassified from FP to HP at 2200–2310 lbs with fuel injection and .425" valve lift limit. · FP Fiat X-1/9 1300 loses 50 lbs to 1665; X-1/9 loses 50 lbs to 1765. · Daimler SP 250 classified in EP at 2165 lbs with 2548 cc OHV 8-cylinder engine. · T2 BMW M2 CS Cup 2020- weight increases from 3625 to 3600 lbs; mandatory Purple power stick added. · T4 BMW 320i 14-15 part number corrected from 20121.140 to E10-20-031-01-22. · Porsche 924 moves from EP to FP Level 1 Prep, classified at 2200 lbs with 1984cc 4-cylinder OHC engine. · EP, FP, HP clarifies percentage weight penalties sum first, then apply to base weight, rounding to nearest pound. · SRF3 alternator pulley restricted to P/N G902130 or G902130A, 12oz minimum weight. · T3 Honda Civic Type-R 2020+ allows brake rotor 45251-TGH-A01 with 25 lb penalty. · T2 Ford Mustang GT 5.0L 15-17 restrictor grows 55mm to 58mm; 2018- grows 53mm to 55mm. · T2 BMW Z4M 06-08 weight increases from 3100 to 3150 lbs. · T2 BMW E92M3 08-14 weight drops 50 lbs to 3425, intake restrictor reduces 3mm to 77mm. · T3 Honda Civic Type-R 2020+ allows brake rotor 45251-TGH-A01 with 25 lb penalty. · 84-87 Mazda 626 reclassified from FP to HP with 2300–2415 lbs weight, 1998cc SOHC, dual 32mm carbs. · FP Fiat X1/9 brake rotors change to 257 (10.1) x 12 (.407) solid disc. · T2 C5 and C6 Corvettes permit specific dry sump kits and minor air dam trimming up to 3.9 cm depth. · T2 Chevrolet Camaro 1LE auto trans gets new gear ratios and 2.77 final drive ratio. · T2 BMW M3 01-06 minimum competition weight drops 100 lbs to 3000. · T2 Chevrolet Camaro SS/1LE model years expanded from 2010–2014 to 2010–2015. · T4 Mini Cooper S (02-04, 05-06) suspension/wheel rules simplified; (07-13) gear ratios changed to 3.31, 2.13, 1.48, 1.14, 0.95, 0.82, final drive to 3.65, brakes to 280 mm. · T4 Ford Mustang V6 05-10 now allows cold air intake. · Mazda 3 S 04-08 classified in EP at 2350 lbs minimum, 2.26L DOHC, 12.0:1 compression, .500" valve lift limit. · FP Volkswagen Golf III and IV intake valves increase to 40.0 mm, exhaust valves to 33.0 mm. · T2-T4 clutch disc and pressure plate must be at least 95% of factory OEM weight. · Spec Corvette newly classified in T2 at 3375 lbs with 53mm restrictor and 3.75" minimum ride height required. · T2 BMW E92 M3 front and rear springs increased to 1000 lbs/in from 800. · T2 Toyota Supra 2020- spring rates limited to 800# front and 1000# rear maximum. · T2-T4 clutch disc and pressure plate must be at least 95% of factory OEM weight. · SRF and SRF3 mandatory identification simplified: removed Ford Performance and Blue Oval decals, kept Hoosier logo placement. · T2 BMW M2 CS Cup 2020- permitted to remove door glass and mechanism. · T4 Ford Mustang V6 05-10 wheels increase from 17 to 18 inches. · T2 BMW M235iR allows 240iR/Evo package with 50 lb penalty, must run DOT tires. · Toyota Supra 2020- newly classified in T2 at 3450 lbs minimum weight with 295 tire and 19-inch wheels. · T2 Honda Civic Type-R gains allowance for PRL cold air intake #PRL PRL-HCR-INT-HVI. · T2 Porsche Carrera S 997.2 (06-08) weight reduced 50 lbs to 3225. · T2 Ford Mustang GT 5.0L (15-17) gear ratios corrected to 3.66, 2.43, 1.69, 1.32, 1.00, 0.65 or 4.17, 2.34, 1.52, 1.14, 0.87, 0.69. · T2 BMW Z4M 06-08 maximum wheel size increases from 18x9 to 18x10 inches. · T2 BMW M2 CS Cup 2020- and M235iR clarify homologation notes for DOT tires and BMW Motorsports components. · Toyota Supra 2020- newly classified in T2 at 3450 lbs minimum weight with 295 tire and 19-inch wheels. · T4 Mazda MX-5 durability rule now applies to T2-T4 instead of T2-T3 only. · T4 Chevrolet Sonic (2011-) spec clarified: 28mm TIR restrictor placement, PCV plug requirement, and allowed suspension parts listed. · T4 Mazda MX-5 06-15 removes front and rear end links from suspension package spec. · T4 BMW Z4 2.5L (03-05) minimum weight reduced from 3100 to 3050 lbs. · T4 2016+ Mazda MX-5 Miata gains allowance for 29mm front and 16mm rear sway bars. · T4 Scion FR-S, Subaru BRZ, and Toyota 86 replace Eibach part 4.10582.880 with 82105.320, 4.10582 and SPC 67660. · T4 Ford Mustang V6 05-10 allows GT 8.8 rear axle with 3.45 or 3.55 ratio at +25 lb penalty. · EP Austin-Healey 3000 Mk. I, II, III now allows TR-6 front calipers and discs as alternate. · FP Volkswagen Golf 1.8 (85-92), Jetta 1.8 (85-92) lose 50 lbs to 1900; Jetta (82-84), Rabbit, Scirocco lose 50-100 lbs to 1733-1803. · BMW M2 CS Cup 2020+ classified in T2 at 3625 lbs with 2979cc engine, 10.5x18 wheels, 295 tires. · T2 and T3 Nissan 350Z and 370Z permit 44011-RC350 rear caliper kit and SZ350 rotors. · T4 Ford Mustang V6 05-10 allows GT 8.8 rear axle with 3.55 final drive, adds 25 lb penalty. · T3 and T4 FR-S, 86, and BRZ year ranges capped: T3 at 2021, T4 at 2017-2021. · BMW M2 CS Cup 2020+ classified in T2 at 3625 lbs with 2979cc engine, 10.5x18 wheels, 295 tires. · T3 and T4 Mazda MX-5 06-15 now allow Mazda Transmission kit part # 0000-02-5700. · T4 Ford Mustang V6 05-10 allows GT 8.8 rear axle with 3.55 final drive, adds 25 lb penalty. · T3 and T4 FR-S, 86, and BRZ year ranges capped: T3 at 2021, T4 at 2017-2021. · FP Volkswagen Golf and Jetta 1.8 lose 50 lbs each, to 1900. HP Jetta GLI engine code removed. · EP, FP, HP Level 1 and Level 2 induction systems: clarified carburetor and fuel injection rules, jets/needles/rods unrestricted in Level 2. · EP Datsun SRL 311U Roadster minimum weight reduced to 1925 lbs from 2000 lbs. · EP Triumph TR8 78-81 weight reduced from 2600 to 2500 lbs. · Honda Civic EX 96-00 classified in FP at 1975 lbs, 1590cc SOHC, 56mm throttle body, valve lift .450" max. · FP adds FAJS carburetor to permitted Weber and auto-type substitutions in two rule sections. · SRF shocks, springs, bump stops sealed; rear springs 412-429 lbs/in P/N 280390 only; previous parts no longer allowed. · T2 BMW E92 M3 (08-14) weight reduced 50 lbs to 3475, with detailed brake, spring, sway bar, and restrictor specs. · T2 Corvette C5 Z06 restrictor sizes increase to 53mm and 58mm; C6 LS2 to 56mm, LS3 to 50mm; Camaro SS/1LE weight drops 75 lbs to 3625; 2016+ Camaro restrictor to 56mm; Mustang GT 11-14 to 58mm, 15-17 to 55mm, 2018+ to 53mm; Viper SRT-10 th… · T3 Alfa Romeo 4C Launch Edition now allowed in Spec Lines. · T3 Alfa Romeo 4C Launch Edition now allowed in Spec Lines. · HP 84-87 Toyota Corolla wheel diameter increases from 13 to 15 inches. · T2 Ford Mustang GT 5.0L and Ecoboost 2.3 sway bar part numbers added to notes. · T2 brake rotors expand from ferrous metal only to 2-piece ferrous disks with aluminum hats, within 5% OE diameter. · T2 Corvette C-5 Z06 loses 50 lbs to 3425; Camaro SS/1LE loses 50 lbs to 3650; Mustang GT and Boss 302 gain 275 to 295 tyres. · T2 Porsche Cayman S, Spyder (10-12) allows 800#/in front and 1000#/in rear springs, cooler ducting, rotor ducting, and specific Porsche and StopTech brake items. · EP BMW Z3 2.5L iron block casting 1738566-C designation removed, wording clarification only. · T2 Ford Mustang EcoBoost and GT 5.0L gain three optional gear ratio sets for competition use. · T4 Scion FRS and Subaru BRZ Solo Spec Coupe final drive ratio changed from 4.30 to 4.10. · Porsche 911 S 67-68 classified in EP at three weight levels: 1800, 1845, or 1890 lbs. · FP Mazda 626 84-87 carburetor spec now specifies two auto-type sidedraft 32mm choke carbs or fuel injection. · Cannot read: letter references external document #27663 not provided. · T2 Porsche Cayman S, Spyder (10-12) gains brake, suspension, and drivetrain upgrades: StopTech calipers, 800#/in front and 1000#/in rear springs, Porsche control arms, PDK allowed. · T4 Mazda RX-8 04-12 now allows OE rear spoiler #F151-V4-920F and OE front air dam #F151-V4-900f-BB. · T4 2006-2015 Mazda MX-5 Club Model now allows non-stock wheels; transmission, differential, LSD remain stock. · Cannot read: letter references external document #27663 not provided. · EP BMW 2.8L, 328i E36/E46, and 325i E36 blocks now iron only; 325i E46 aluminum only. · FP Volkswagen Scirocco E&O adds four engine variants with weights 1520–1853 lbs and displacements 1471–1780 cc. · SRF3 shock absorber brand restriction removed; all shocks must be sealed by Enterprises. · 2004 Mercedes Benz CLK 320 Coupe classified in T4 at 3200 lbs with 3299cc engine and Eibach PN# 2563.140 springs allowed. · T1 and T2 Corvettes may convert leaf spring suspension to coilover with 800 lb max spring rate allowed. · 2004 Mercedes Benz CLK 320 Coupe classified in T4 at 3200 lbs with 3299cc engine and Eibach PN# 2563.140 springs allowed. · 1990-1994 Mazda Protege classified in FP Pre at 2150–2258 lbs with 1839cc DOHC engine, fuel injection. · HP Mini Cooper model year ranges for convertibles revised: 02-06 now includes 05-08, 07-13 now includes 09-15. · SRF3 bump stop now must be SCCA P/N 280407 only, no modifications, optional, max one per shock. · SRF shock absorber bump stop clarified: only SCCA P/N 280407 allowed as delivered, maximum one per shock, effective 05/01/2020. · T2 BMW E92 M3 08-14 gains approved AP Racing brake kit part numbers 13.01.10038 front, 13.01.10053 rear. · T2 Chevrolet Corvette C5 Z06 loses 50 lbs with 45mm restrictor, to 3175; 50 lbs with 55mm restrictor, to 3350. · T3 BMW Z3 M & Coupe 1998-1999 weight reduced from 3350 to 3150 lbs. · T4 06-15 Mazda MX-5 now allows header part numbers 0000-06-5407 or 0000-06-5407-NC. · T3 BMW Z3 M & Coupe 1998-1999 weight reduced from 3350 to 3150 lbs. · EP Caterham 7 Spec Line removes redundant suspension note, clarifies engine prep limits and comp ratio to 10.0:1. · 1989-90 Nissan 240-SX SOHC added to FP Level 2 with 2400-2520 lbs weight range. · T2 Porsche 911 997.2 allows GT3 Cup front fascia with 75 lb penalty; OEM rear deck lid and GT3 Cup splitter now required or prohibited. · T2 Ford Mustang GT 5.0L 15-17 transmission gear ratios corrected to two allowed options. · FP Volkswagen Jetta, Rabbit, Scirocco 1457-1853cc reclassified with inlet valve 40.0mm, exhaust 33.0mm, weights 1520-1853 lbs. · HP Datsun 510 gains 40 DCOE carburetor option alongside existing 40 DCN and 36mm DCNVH choices. · Porsche 914-4 2.0L classified in FP Prep 2 at 2030-2132 lbs with 1968cc OHV engine, 11.0:1 compression limit, .450" valve lift limit. · FP Ford Fiesta 78-80 weight reduced 130 lbs to 1660. · T2 Porsche 911/997 (06-08, 09-12, Carrera S 06-08) aero rules relaxed; 997.2 adds 60mm restrictor and PDK +100lbs option. · T4 Honda Civic Si 12-13 and 14-15 now allow H&R and HPD springs up to 700 pounds with 47mm restrictor. · T4 Ford Mustang V6 05-10 springs now permitted max 500 lbs front and 400 lbs rear. · HP Datsun 1200 carburetor choke size increases from 26mm to 30mm. · Pontiac Solstice GXP and Saturn Sky move from T2 to T3; wheels widen to 18 x 9.5 inches, Sky weight drops to 3200 lbs. · T2 cars now allowed to use ferrous metal 2-piece brake rotors within 5% of OE diameter. · Mazda RX-8 Base/R3/Sport/GT (04-12) classified in T3 effective 2020-02-01. · T2 Nissan 370Z gains alternative Stoptech brake kit option with 50 lb weight penalty. · T2 Ford Mustang Ecoboost 2.3 loses 100 lbs to 3400, wheels widen to 19 x 11, intercooler TIR increases to 50mm. · T2 Mustang GT5.0L gets 19x11 wheels instead of 18x11, Brembro BBK weight penalty removed. · T4 Ford Mustang V6 05-10 allowed aluminum driveshaft, any LSD, and Ford brake kit M-2300-D. · Pontiac Solstice GXP and Saturn Sky move from T2 to T3; wheels widen to 18 x 9.5 inches, Sky weight drops to 3200 lbs. · Mazda RX-8 Base/R3/Sport/GT (04-12) classified in T3 effective 2020-02-01. · T4 Mazda3 14-18 gains permitted modifications: springs to 800/1000 lbs, 15 lb wheels, cold air intake, camber plates, 25mm rear bar, mirrors, CorkSport arms, header, specific calipers and rotor. · T4 allows aftermarket OEM coolant expansion tanks with no other functional purpose. · T4 Mazda MX-5 Club Model 06-15 now allows aftermarket power steering reservoir. · T4 Subaru BRZ and Scion FR-S allowed factory installed wings. · T4 now permitted to use any OEM diameter clutch disc and pressure plate, previously T2-T3 only. · Chevrolet Sonic 2011+ added to T4 at 2800 lbs with 1364 cc engine and 225 max tire size. · T4 Mazda MX-5/Miata 1999-2005 minimum weight reduced 50 lbs to 2400. · FP and EP Mazda Miata models standardized to 55mm throttle body diameter; brake spec clarified. · FP Mazda Protégé ES 01-03 newly classified at 2350–2468 lbs with 1991cc 4-cyl DOHC, fuel injection, 11.0:1 compression, .450 in. valve lift limit. · T2 requires onboard fire system; T3 and T4 may have one per GCR 9.3. · T3 Ford Mustang EcoBoost 2015- gains three transmission gear ratio options. · T2 Chevrolet Camaro SS/1LE (10-14) adds Dailey Engineering dry sump P/N 20-02-0666-ASSY and other approved parts. · T2 Camaro SS 1LE gains approval for half shafts Drive Shaft Shop RA-5424 and RA-5425. · T2 Ford Mustang Boss 302 restrictor 54mm to 56mm; GT 5.0L 11-14 restrictor 52mm to 54mm; GT 5.0L 15-17 restrictor 50mm to 52mm; C5 Z06 weight 3525 to 3475 lbs; C6 weight 3450 to 3400 lbs; Porsche 911 997.2 restrictor 60mm to 57mm. · T2 Chevrolet Camaro 1LE 2016- weight reduced from 3600 to 3550 lbs. · T2 Honda Civic Type-R (2017-) weight reduced from 3050 to 3000 lbs; tire TIR requirement increased from 50mm to 51mm. · Mazda RX-8 Base/R3 (04-12) reclassified in T3 and T4 to include Sport and GT variants. · Toyota 86 GT (2017-) added to T3 and T4 Spec Line. · T2 requires onboard fire system; T3 and T4 may have one per GCR 9.3. · T3 Ford Mustang EcoBoost 2015- gains three transmission gear ratio options. · T4 BRZ, FR-S, and 86 maximum tire size reduced from 245 to 225. · T4 Mazda MX-5 Club Model 06-15 minimum weight cut from 2625 to 2550 lbs. · Mazda RX-8 Base/R3 (04-12) reclassified in T3 and T4 to include Sport and GT variants. · Toyota 86 GT (2017-) added to T3 and T4 Spec Line. · SRF rain and brake rule wording updated; supersedes GCR 9.3.32.B.2 effective 1/1/202 through 12/31/2024. · FP and HP Honda Civic and CRX 1988–91 track specifications corrected to 61.3/61.7 inches. · EP, FP, HP cylinder head rules reorganized for clarity; no performance change. · SRF bans tire warmers and cooling methods other than natural air convection or conduction. · SRF front nose weight minimum reduced from 35 to 32 lbs. · SRF3 reclassified as Spec Racer Ford 3 with 1.6L conversion; SRF2 becomes Regional Only Class. · FP and HP Austin-Healey Sprite Mk I and MG Midget variants may replace rear bodywork aft of cockpit with stock-appearing alternate material components. · EP Mazda MX-5 Global Cup classification year changes from 16-18 to 16-19. · Production suspension rule clarifies spindles, hubs, bushings, bearings, ball joints unrestricted. · Production carb rules clarified: carburetor options, fuel injection throttle body dimensions, and intake manifold restrictions reorganised and refined. · EP, FP, HP carburetors clarified: jets, needles, metering rods, needle valves unrestricted; choke parts removable; permitted optional carburetors listed. · T2-T4 spare tire/wheel rules clarified: removable covers can be removed with hardware and bracketry. · T2-T4 spare tire/wheel rules clarified: removable covers can be removed with hardware and bracketry. · T4 Mazda MX-5 Club (06-15) gains suspension package with 100 lbs weight increase, allows RX8 hubs and SM5 suspension, permits non-OEM LSD with 50 lbs penalty. · EP Mazda MX-5/Miata eligibility years expanded from 1999-2002 to 1999-2005. · SRF drivers may now use Dash Windscreen Kit P/N 1180103 or P/N 180102. · T2 Cadillac CTS-V classification expanded from 06-07 to include 04-05 model years. · T2 Cadillac CTS-V 06-07 allowed to use Hotchkiss sway bars up to 36mm front, 25mm rear. · T2 Cadillac CTS-V 06-07 requires 57mm flat plate restrictor. · T2 Ford Mustang GT 5.0L tire size reduced from 315 to 295. · T4 Toyota MR-2 Spyder 16V DOHC years corrected from 01-05 to 00-07. · SRF3 nose assembly must use approved multi-piece design; no modifications allowed except as specified. · T2 2018+ Audi TT RS gains suspension and intercooler allowances: 30mm front sway bar, 28mm rear, 1200lb/in springs, aftermarket intercooler. · T2 Honda Civic Type-R 2017- weight rises 2900 to 3050 lbs, TIR increases 38mm to 50mm. · T4 Mazda Protégé ES 2000 now allows piggyback ECU tuning device; OBD2 requirement waived. · T4 Mazda MX5 Club Model 06-15 allows suspension package with 100 lbs weight increase including helper springs. · SRF3 brakes now allow Hawk Blue 9012 pads P/N 801993 only; shocks simplified to Penske P/N 280396 sealed assembly only, with optional SCCA Enterprises bump rubber P/N 280407 from 05/01/2020. · EP, FP, HP clarified: tapered holes in ball joints now allowed for bolt conversion; wheel bearings and hubs unrestricted at any wheel. · EP open cars may now use aftermarket hardtops if they retain OEM appearance; specific model hardtop allowances removed. · T2 Mustang GT anti-roll bars may now be removed or disconnected, previously required as manufactured. · T4 BMW 323 (98-00) newly classified at 3450 lbs with 50mm flat plate restrictor and M52TUB25 engine required. · FP Dodge Daytona/Chrysler Laser added at 2100/2153/2205 lbs; Shelby Charger/Omni 024 weight reduced to 2100/2153/2205 lbs. · T1-LP Ford Mustang GT 5.0L 2018+ classified at 3400 lbs with 65mm flat plate restrictor. · T2 Audi TT RS (2018-) newly classified at 3400 lbs minimum weight with 19-inch wheels and 275 tire size. · T2 2017 Civic Type R allows any sway bar front/rear up to 30mm, front springs to 800lb, rear to 2000lb. · T4 Mazda MX-5 Club (06-15) and (2016-), T3 MX-5 Cup and Miata (2016-) hardtop rules clarified; wording changes to permitted parts and specifications. · T2, T3, T4 now allow any thermostat serving only OE intent, previously restricted. · T2 Ford Mustang Boss 302 (12-13) weight drops 50 lbs to 3500. · T2 Corvette C6 Coupe/Grand Sport removes 3.0 degrees MAX front camber restriction. · T2 Pontiac Firebird and Chevrolet Camaro SS (98-02) permitted spring relocation to shock. · T3 and T4 Mazda MX-5 Miata eligibility capped at 2018 model year, effective 2019-03-01. · Ford Mustang GT 5.0L 2018+ classified in T2 at 3600 lbs with 50mm restrictor, 19x11 wheels, 315 tyres. · T4 Mazda MX-5 Club (06-15) and (2016-), T3 MX-5 Cup and Miata (2016-) hardtop rules clarified; wording changes to permitted parts and specifications. · T2, T3, T4 now allow any thermostat serving only OE intent, previously restricted. · T3 and T4 Mazda MX-5 Miata eligibility capped at 2018 model year, effective 2019-03-01. · T4 Honda Civic Si 2012-2015 permitted sway bars increased to 32mm front and rear. · T4 Ford Fiesta ST years corrected to 14-; T4 Fiat 124/Abarth Edition years added 16-18; battery rule clarified. · T2 Porsche Cayman S/GTS model years expanded from 13-14 to 13-15, now includes GTS variant. · T2 Honda Civic Type-R 2017- allows Cuztom Tuning FG-CIV16-V3-TR-BK alternate grill. · T1-T3 spec cars receive clarifications on permitted modifications, documentation requirements, and rule conformance; no performance changes. · T2-T4 subframe bushings may now be replaced with non-spherical bushings of any material. · T4 Ford Fiesta ST years corrected to 14-; T4 Fiat 124/Abarth Edition years added 16-18; battery rule clarified. · T4 Fiat 124 Abarth Edition restrictor changes from 29mm flat plate to 30mm TIR. · T1-T3 spec cars receive clarifications on permitted modifications, documentation requirements, and rule conformance; no performance changes. · T2-T4 subframe bushings may now be replaced with non-spherical bushings of any material. · Scion FR-S and Subaru BRZ 13-16 Solo Spec Coupes added to T4, both 1998cc, 2570 lbs, 225/45/17 tires.showhide
FP Effective date for Jan 2025 GCR updates #37654inductionslowerEP BMW Z3 2.5L requires 52mm flat plate intake restrictor; Z3 2.8L 55mm; 328i/is E36 58mm; 328i/ci E46 58mm; 325i/is E46 56mm; 325i/is E36 56mm; 325is M-Technic 56mm.
T2 Mustang Update backdate #37275inductionunclearT2 Mustang GT 5.0L combines 2015-17 and 2018-23 with different restrictors: 63mm for Gen 2, 60mm for Gen 3.
T2 BOP Adjustment for 2016 - Camaro SS/1LE #37434weight +100 lbsslowerT2 Chevrolet Camaro 1LE gains 100 lbs to 3600, restrictor increases to 62mm FPR.
T2 BMW M235iR TCS CHANGE REQUEST #37470wordingneutralT2 BMW M235iR (-2016) now permits oil cooler, radiator per touring rules, and silicone charge pipe.
T2 Request to Classify Club Spec in Appropriate Touring Classes #37523cars addedneutralFord SCCA Club Spec Mustang classified T3 at 3350 lbs with driver; Mazda SCCA Club Spec MX-5 classified T4 at 2500 lbs with driver.
T4 Ford Mustang V6 (05-14) #37516wordingneutralT4 Ford Mustang V6 (05-14) final drive set to 3.45, GT/CS front bumper cover permitted with front fascia.
T4 Request to Classify Club Spec in Appropriate Touring Classes #37523cars addedneutralFord SCCA Club Spec Mustang classified T3 at 3350 lbs with driver; Mazda SCCA Club Spec MX-5 classified T4 at 2500 lbs with driver.
FP Request to Reduce Weight of BMW 325i/is E30 (84-91) Spec Line #37119weight -50 lbsfasterEP BMW 325i/is E30 (84-91) weight reduced 50–52 lbs across three spec lines to 2150, 2204, 2258.
FP Fix Error in Spridget Spec Line #37437wordingneutralFP Spridget and Midget 1275cc and 1500cc spec line corrections to bore, stroke, displacement, and valve sizes.
FP Create ruleset that allows GTL cars to run in FP #37485cars addedneutralF Production now allows GT-Lite cars meeting Appendix N specifications to compete, effective 2025-01-01.
T2 Remove spec lines that have expired #37269removedneutralT2, T3, T4 remove nine, nine, and thirty-six expired spec lines respectively, effective 2025-01-01.
T2 BoP for the Various Mustangs #37185weight -50 lbsfasterT2 Ford Mustang GT 5.0L (11-14) weight reduced from 3575 to 3525 lbs.
T2 Spec Corvette Line Clarification. #37441wordingneutralT2 Spec Corvette clarifies braking, tires, cooling, suspension, and Spec+ upgrades; SC-3200, SC+-3300 lbs.
T4 Remove spec lines that have expired #37269removedneutralT2, T3, T4 remove nine, nine, and thirty-six expired spec lines respectively, effective 2025-01-01.
T2 Redundant Verbiage Regarding Mustang Spec Lines for Driveshaft #36484wordingneutralT2 and T3 Mustang spec lines remove redundant driveshaft alternate/aluminum allowance wording.
T2 Request Less Restriction for Ls-3 Engined C6 Corvette #36810inductionfasterT2 Chevrolet Corvette C6 LS3 restrictor increases from 53mm to 56mm flat plate.
T2 Fuel Emissions Components #37076wordingneutralT2, T3, T4 fuel cell installations may remove charcoal canisters, emissions valves, and sensors.
T2 fix brake wording #37129wordingneutralT2, T3, T4 brake component wording clarified: 2-piece rotors allowed in T2 within 5% OE diameter, T3 within 2% OEM diameter.
T2 Evaporative emissions systems #37130wordingneutralT2, T3, T4 fuel cell cars may remove charcoal canisters, emissions valves, and sensors.
T2 Move Spec Boxster to T4 #37158cars addedneutralPorsche Spec Boxster moves to T4, minimum weight 2750 lbs, requires 3 Super Tour events before Runoffs eligibility.
T2 Corvette Wheels #37169tyres & wheelsfasterT2 Chevrolet Corvette C6 Coupe/Grand Sport wheels widened to 18×11 or 19×13.
T2 BMW 320i Spec Line #37204wordingneutralT4 BMW 320i 14-15 Spec Line expires 12/31/24 removed; Turner Motorsports intercooler #024703TMS02 allowed.
T2 Classification for a 2005 Cadillac CTS 3.6 liter 6 speed manual #37224cars addedneutralCadillac CTS 02-07 3.6L classified in T3.
T2 Please Consider Allowing Update to the C5 Corvette #37298engineunclearT2 Corvette C5 Z06 restrictor split by engine: LS1 59mm, LS2 63mm, LS3 56mm FPR.
T2 Major error in lane, but nobody ran it. #37302removedneutralT2 Chevrolet Corvette Z06 (06-12) Spec Line deleted entirely.
T4 Redundant Verbiage Regarding Mustang Spec Lines for Driveshaft #36484wordingneutralT2 and T3 Mustang spec lines remove redundant driveshaft alternate/aluminum allowance wording.
T4 R53 Mini Cooper S Weight Reduction Request #36612enginefasterT4 Mini Cooper S R53 now allows Alta 15% Pulley #AMPENG20X.
T4 Allowable Wheel Offset #36855wordingneutralT4 removes restriction on aftermarket wheel weight minimum of 15 lbs.
T4 Fuel Emissions Components #37076wordingneutralT2, T3, T4 fuel cell installations may remove charcoal canisters, emissions valves, and sensors.
T4 2019-2024 Mazda 3 for T4 #37077cars addedneutralMazda 3 (19-24) newly classified in T4 at 2850 lbs with 17×8 wheels and 245 tires.
T4 fix brake wording #37129wordingneutralT2, T3, T4 brake component wording clarified: 2-piece rotors allowed in T2 within 5% OE diameter, T3 within 2% OEM diameter.
T4 Evaporative emissions systems #37130wordingneutralT2, T3, T4 fuel cell cars may remove charcoal canisters, emissions valves, and sensors.
T4 Allow Spec MX5 upgrade kit for 2009-11 RX8 S2 Transmision #37140wordingneutralT3 and T4 Mazda RX-8 and MX-5 permit transmission kit #0000-02-5700.
T4 Move Spec Boxster to T4 #37158cars addedneutralPorsche Spec Boxster moves to T4, minimum weight 2750 lbs, requires 3 Super Tour events before Runoffs eligibility.
T4 3.7 Mustangs to T4 #37188cars addedneutralFord Mustang V6 (05-14) newly classified to T4 with 50mm restrictor, 3400 lbs minimum weight.
T4 BMW 320i Spec Line #37204wordingneutralT4 BMW 320i 14-15 Spec Line expires 12/31/24 removed; Turner Motorsports intercooler #024703TMS02 allowed.
T4 MX5 2006-2015 NC Help #37221otherunclearUnable to summarize: rule changes specified in letter #37281, not provided.
T4 Classification for a 2005 Cadillac CTS 3.6 liter 6 speed manual #37224cars addedneutralCadillac CTS 02-07 3.6L classified in T3.
T4 Civic SI in T4 #37248weight -50 lbsfasterT4 Honda Civic Si 06-11 minimum weight drops 50 lbs to 2900, restrictor clarified.
T4 2006-2015 T4 NC Mx5 spec line #37278wordingneutralT4 NC MX-5 06-15 removes SM5 suspension allowance, clarifies Mazda Motorsports LSD part number, adds weight penalty for other LSDs.
T4 ND MX-5 wheel allowance #37279tyres & wheelsunclearT4 Mazda MX-5 Miata/Club (16-18) wheel size changes to 17 x 7.5 inches.
T4 T4 BOP #37281weight +75 lbsslowerT4 Mazda RX-8 gets 59mm restrictor and 3200 lbs; MX-5 Club drops to 2550 lbs.
T4 Allow 7.5 #37286tyres & wheelsneutralT4 Mazda MX5 Miata/Club/RF 19-24 wheel size changes to 17 x 7.5.
FP 1275 HP Spridget Level 2 Only #36518enginefasterHP Sprite and Midget 1275cc and 1098cc Level 2 compression ratio raised to 12.0:1.
T2 Spec Corvette Change for T2 #37127tyres & wheelsneutralT2 Spec Corvette now allows 295 R compound DOT tires as alternative to Nankang NS-2R.
T4 Bop Request 06-11 Honda Civic Si #37013wordingneutralT4 Honda Civic Si 06-11 permitted to use LSD per category rules.
FP Errors/emissions Honda Civic/CRX #36700enginefasterFP Honda CRX/CRX Si 84-87 block material changes from Iron to Alum.
SRF3 Update SRF3 Air Filter Rule #36681wordingunclearSRF3 air filter rule removes K&N RC-9160 option, leaving only P/N WM301020 allowed.
SRF3 Hoosier Tire Decal Placement #36739wordingneutralSRF3 Hoosier logo placement changes from four decals to three decals in different locations.
SRF3 Update to Letter 36619 with new Hoosier Contingency Decal Info #36624wordingneutralSRF Hoosier decal requirement reduced from four decals in specific locations to three decals with simpler placement rules.
FP Errant entry in HP production line item #36231wordingneutralHP Volkswagen Golf and Jetta 85-92 track correction: front 1537mm (60.5in), rear 1529mm (60.2in).
SRF3 Update Rain Tire Rule and Hoosier Decal Placement #36436tyres & wheelsslowerSRF wet tires: P185/60R13 H20/W2 option removed; P185/65R13 W2 front now required with P205/60R13 W2 rear.
T2 Errors #36214other -75 lbsunclearT2 Corvette C6 LS2 restrictor increases to 63mm; Camaro 1LE weight drops to 3500 lbs, restrictor tightens to 58mm FRP.
T2 Subaru Appeal #36258wordingneutralT2 Subaru Impreza WRX STi (03-07) and (08-11) expiration notes removed.
T2 S550 Brakes #36571otherfasterT2 Ford Mustang 5.0L gets 100 lb weight reduction with 4-piston Brembo brakes and 355mm rotors; EcoBoost brake note removed.
T4 T4 Camaro V6 weight reduction #36232weightfasterT4 Chevrolet Camaro V-6 (96-02) weight reduced from 3250 lbs to 3150 lbs.
T4 BOP adjustment for ND MX5s #36345weight -50 lbsfasterT4 Mazda MX-5 Miata/Club 16-18 drops 50 lbs to 2650; 19-24 RF drops 50 lbs to 2750.
T2 Mustang T2/T3 #35877wordingunclearFord Mustang GT 5.0L and V6 now permit Track/Performance Package parts in T2 and T3.
T2 S550 Brakes #35926weightslowerT2 Ford Mustang S550 5.0 Gen2/Gen3 gains 100 lbs with stock or Brembo 355mm brakes.
T2 T2-T4 Driveshaft Mistake...? #36050weightfasterT2-T4 Ford Mustangs: remove 25 lbs penalty for non-OEM driveshaft, clarify alternate driveshaft allowances.
T2 request for allowance of 6 piston calipers for T2 C5 corvettes #36126suspension & brakesfasterT2 Corvette C5, Camaro SS, Firebird, Solstice GXP, C6 allow four or six piston front calipers.
T2 B8/8.5 Audi S4 T3 and T2 #36195cars addedneutralAudi S4 (2000-2002) moves to T3 with 3400 lbs minimum weight, 38mm turbo inlet restrictor required.
T4 Mustang T2/T3 #35877wordingunclearFord Mustang GT 5.0L and V6 now permit Track/Performance Package parts in T2 and T3.
T4 Homologation of car to T4 #36030cars addedneutralMercedes C300 4Matic 2008-2011 homologated to T4 at 3,725 lbs with 18x8.5 wheels, 245 max tires, 3.27 final drive.
T4 T2-T4 Driveshaft Mistake...? #36050weightfasterT2-T4 Ford Mustangs: remove 25 lbs penalty for non-OEM driveshaft, clarify alternate driveshaft allowances.
T4 MINI Cooper S Spec Lines Corrections. #36086wordingneutralT4 Mini Cooper S (02-04) deleted; (05-06) model year corrected to R53; (07-13) R56 simplified specs; (2014-2023) added with spring rates.
T4 Allow Removal of Sound Tubes #36130inductionfasterT4 OEM intake chambers, resonators and acoustic devices may be removed if ports sealed and before restrictor.
T4 B8/8.5 Audi S4 T3 and T2 #36195cars addedneutralAudi S4 (2000-2002) moves to T3 with 3400 lbs minimum weight, 38mm turbo inlet restrictor required.
FP NIssan 300ZX Z31 to EP #35830cars addedneutralNissan 300ZX 84-89 classified to EP at 2550 lbs minimum, 2960cc 6-cyl SOHC, fuel injection, 12.0:1 compression limit, 0.500" valve lift limit.
FP RX7 1993 and Up Request In EP Spec Lines, classify #36031cars addedneutralMazda RX-7 92-97 newly classified EP Prep Level 2 at 2200–2310 lbs with 13B 6-port rotary engine.
FP Clean-up Multiple EP RX-8 Spec Lines In EP #36156wordingneutralEP Mazda RX-8 (04-11) alternate spec line removed; one primary line remains.
SRF3 SRF3 Alternator Pulley Update In #36095weightfasterSRF3 alternator pulley minimum weight reduced from 12 oz to 11 oz.
T4 Allow OEM Front Spoiler 06-08 Miata in T4 #35941aerofasterT4 Mazda MX-5 Club 06-15 now permits OEM front spoiler NF51-V4-900F.
T4 T4 Mustang Weight Reduction In T4 Spec #36051weight -50 lbsfasterT4 Ford Mustang V6 (05-10) weight reduced 50 lbs to 3225.
T4 R53 Mini Cooper S spec line request In #36056otherfasterT4 Mini Cooper S 02-04 and 05-06 now allow Milltek exhaust manifold #SSXM459 and 25mm rear sway bar.
FP Request to Replace CRX Plastic Panels #35876wordingneutralFP Honda CRX 84-87 can replace plastic front header, rocker skirt, door cap panels with stock-appearance replicas in alternate materials.
FP FP data and parity #35896inductionslowerFP Acura Integra and Honda Civic models now require 55mm Flat Plate Intake Restrictor.
T2 Allow T4 and T3 RX8 to Disable/Remove Factory Oil Inj. #35761engineunclearT3 and T4 Mazda RX-8 may remove or disable factory oil injection system.
T2 Competition Adjustment Request/Wheel Size of E46 #35895tyres & wheelsfasterT2 BMW M3 01-06 max wheel size increases from 18 x 9 to 18 x 10 inch.
T2 Driveshafts #35916weightslowerT2, T3, T4 driveshafts may use alternative materials or one-piece units; non-OEM adds 25 lbs.
T4 Allow T4 and T3 RX8 to Disable/Remove Factory Oil Inj. #35761engineunclearT3 and T4 Mazda RX-8 may remove or disable factory oil injection system.
T4 2023 ND2 Miata Classification and Allowances #35837weightslowerT4 Mazda MX5 Miata/Club/RF year range extended to 2024, suspension package permitted with 100 lbs weight increase.
T4 Errors and Omissions for 06-09 VW Rabbit Rotor #35851suspension & brakesfasterT4 Volkswagen Rabbit 2.5 (06-09) front brakes increase from 228 to 288 vented disc.
T4 Driveshafts #35916weightslowerT2, T3, T4 driveshafts may use alternative materials or one-piece units; non-OEM adds 25 lbs.
T4 GCR ERROR - letter not properly applied to GCR #35999suspension & brakesfasterT4 Mazda MX-5 Miata/Club 16-18 removes differential stock requirement, allows up to 500lb front and 300lb rear springs.
T2 Brake Request for 2009 Porsche Cayman #35723suspension & brakesslowerT2 Porsche Cayman S 06-09 allows StopTech ST60/ST40 brake kit with 50 lb penalty.
T4 Corrections to T4 RX8 Spec line #35767wordingneutralT4 Mazda RX-8 allows Mazdaspeed radiator, coil spring kit, OE rear spoiler, front air dam, springs to 700 lb front/400 lb rear, oil metering pump bypass, sway bars to 32 mm front/19 mm rear.
T2 370Z Brake Rotor Size Correction #35487suspension & brakesneutralT2 and T3 Nissan 370Z brake rotors enlarged: front 320x28 to 355x32mm, rear 320x16 to 350x20mm vented.
T2 Letter #35154 2018+ Mustang GT Expansion #35488suspension & brakesneutralT2 Mustang GT 5.0L 2018+ now permits BMR rear upper control arm camber links part #UTCA064.
T4 Allow any 400lb rear spring in the RX8 #35433suspension & brakesneutralT4 Mazda RX-8 rear spring opens to any 400lb, was specific part numbers only.
T4 370Z Brake Rotor Size Correction #35487suspension & brakesneutralT2 and T3 Nissan 370Z brake rotors enlarged: front 320x28 to 355x32mm, rear 320x16 to 350x20mm vented.
FP Update 1988-1991 Civic to Match 1988-1991 CRX #35399weightfasterHP Honda Civic 1.5 (88-91) weight reduced to 2175 lbs base, 2229 lbs with power adder, 2284 lbs with two.
T2 2015+ Mustang Sway Bar and A-Arm Request #35154suspension & brakesneutralT2 Mustang GT 5.0L 15-17 now permits BMR rear upper control arm camber links part #UTCA064.
T2 Brake Kits #35245otherneutralT2 Chevrolet Camaro SS, 1LE, Corvette C5/C6, Z06, and Pontiac Firebird, Solstice GXP now allow four or six piston front calipers.
T2 Runoffs wording on Caddy in T2 #35377wordingneutralT2 Cadillac CT4-V Blackwing Runoffs qualification requirement removed.
T2 More Car Lightening Stuff #35319weightfasterT2, T3, T4 battery replacement wording simplified; OEM weight tolerance requirement removed.
T2 Inclusion of B-C spec cars in T4 #35374cars addedneutralT4 now permits C-Spec cars to compete alongside B-Spec cars.
T2 T2-T4 Set expiration dates on spec lines #35378wordingneutralT2-T4 spec lines for 46 cars expire 12/31/24; appeal required to continue.
T2 Reply to letter #35161 and #31661 #35384weight +75 lbsslowerT2 Chevrolet Camaro 1LE minimum weight increases to 3575 lbs, restrictor plate widens to 60mm.
T4 More Car Lightening Stuff #35319weightfasterT2, T3, T4 battery replacement wording simplified; OEM weight tolerance requirement removed.
T4 ND Missed Items #35352wordingneutralT4 Mazda MX-5 Miata/Club (16-18) and (19-21) permitted to replace 3rd and 4th gears with specific parts.
T4 Inclusion of B-C spec cars in T4 #35374cars addedneutralT4 now permits C-Spec cars to compete alongside B-Spec cars.
T4 T2-T4 Set expiration dates on spec lines #35378wordingneutralT2-T4 spec lines for 46 cars expire 12/31/24; appeal required to continue.
FP FP data #35060weight +25 lbsslowerFP Acura Integra LS and Honda Del Sol VTEC minimum weights increase 25–78 lbs across all configurations.
FP Request to Review Z3 2.5 Spec Line #35073weight +50 lbsslowerEP BMW Z3 2.5L weight increases to 2500 lbs, 2563 lbs with turbo, 2625 lbs with supercharger.
FP Corrections to Honda Spec Lines in FP #35250wordingunclearFP Honda throttle body specs corrected: Civic 1.5 to 42", Si to 55", CRX variants adjusted.
FP Miata Alternate Head #35253weight -50 lbsfasterEP Mazda MX-5 1.8L 1990-97 minimum weight drops to 2150 lbs; 1994-97 variants to 2000, 2050, 2100 lbs respectively.
FP Honda S2000 throttle body #35272inductionfasterEP Honda S2000 fuel injected throttle body inside diameter increases from 62mm to 64mm.
FP Correction within Triumph TR8 Spec Line #35315wordingneutralEP Triumph TR8 dry sump allowance moved from carburetor line to notes section.
FP Correction to EP 924S/944 Spec Line #35317wordingneutralEP Porsche 944/924S 2.5L and 2.7L weight minimums corrected: 2479cc to 2306/2363 lbs, 2681cc to 2358/2415 lbs.
SRF3 Update SRF Rain / Brake Rule #34706wordingneutralSRF rain/brake light now requires Super Bright LEDs Inc. P/N PT-STRB-R24 with specific connector and rain light switch.
SRF3 Update SRF Brake Light Rule v1 #34853wordingneutralSRF requires Super Bright LEDs P/N PT-STRB-R24 rain/brake light with strobing capability and specific wiring.
T2 Rebalance Blackwing Cadillac T2 #35079tyres & wheelsfasterT2 Cadillac CT4-V Blackwing rear wheels widen from 18 x 10 to 18 x 11.
T2 M2 CS RACING #35130weight -50 lbsfasterT2 BMW M2 CS Cup drops 50 lbs to 3550; M235iR drops 50 lbs to 3300.
T2 Spec Corvette in T2 #35139weight -175 lbsfasterT2 Spec Corvette minimum weight drops 175 lbs to 3200, tire rules tighten to Nankang NS-2R only.
T2 T2 Viper BoP #35155tyres & wheelsslowerT2 Dodge Viper SRT-10 rear tyre narrowed from 345/30 to 335/30.
T2 BOP Adjustment for 5.0L Mustangs #35156weight +75 lbsslowerT2 Ford Mustang GT 5.0L three generations gain 50-75 lbs minimum weight; restrictors increase to 58-60mm.
T2 Take at Look at T-2 BOP #35161weight -50 lbsfasterT2 Chevrolet Camaro 1LE minimum weight drops 50 lbs to 3500, restrictor opens to 58mm flat plate.
T2 C5 Corvette Spec Line Oversight #35169inductionfasterT2 C5 Z06 removes restrictor note from weight; C5/C6 Corvettes increase restrictors to 59mm, 63mm LS2, 53mm LS3.
T2 Requested Update of Model Years of 370Z #35231wordingneutralT3 Nissan 370Z model years expanded to include NISMO Edition through 2022.
T4 Mazda MX-5 ND1 Spec Line Request #34232weight +50 lbsslowerT4 Mazda MX-5 ND1 minimum weight increases 50 lbs to 2700; suspension springs now allow up to 500 lb front, 300 lb rear.
T4 BRZ/FRS/86 Spring Allowance #35038wordingneutralT4 BRZ/FRS/86 spring allowance clarified: 225 lb front and 300 lb rear springs permitted; non-OEM LSD allowed with +50 lbs penalty.
T4 TSX Allowance #35219aerofasterT4 Acura TSX 2004-2008 now allows header.
T4 Requested Update of Model Years of 370Z #35231wordingneutralT3 Nissan 370Z model years expanded to include NISMO Edition through 2022.
FP Porsche 944/924S Rule Change Request #35002cars addedneutralEP Porsche 944/924S combines 2.5L and 2.7L variants with new weights: 2250–2415 lbs depending on engine and year.
FP FP and HP Toyota Corolla #35030weight -43 lbsfasterFP Toyota Corolla 2TC loses 43 lbs to 1810; HP Corolla loses 50–52 lbs to 1910–2006.
T2 M2 CS RACING #35122aeroneutralT2 BMW M2 CS Cup 2020- permitted to add hood vents conforming to 9.1.9.2.D.8.a.7.
SRF3 SRF Radiator Rule Update #34805wordingneutralSRF radiator rule clarified: P/N 480466 replaceable with Automotive P/N 1R698, CU698 or manufacturer equivalent with documentation.
T4 Inclusion of similar car. (CLK 320) #34626cars addedneutralT4 Mercedes Benz CLK 320 Coupe model years expand to 2000-2007, C320 Sedan added.
T2 Corvette LS2 Restrictor Plate Adjustment #34456inductionfasterT2 Chevrolet Corvette C6 LS2 restrictor plate increases from 58mm to 60mm flat plate.
T2 Blacking Cadillac Fuel Capacity #34624wordingneutralT2 Cadillac CT4-V Blackwing permitted to use Radium fuel surge tank behind fireproof bulkhead.
T2 Rules Clarification for Mazda RX8 Spec Line #34395wordingneutralT3 Mazda RX-8 removes transmission/final drive pairing requirement; T4 removes same requirement, adds Mazdaspeed radiator and coil spring kit.
T2 rule book corrections #34437otherfasterT3 BMW 320i (14-15) gains aftermarket intercooler permission; T4 loses it.
T2 Ride Height Correction for the T3 Solstice. #34615wordingneutralT3 Pontiac Solstice GXP minimum ride height set to 3 inches.
T4 Rules Clarification for Mazda RX8 Spec Line #34395wordingneutralT3 Mazda RX-8 removes transmission/final drive pairing requirement; T4 removes same requirement, adds Mazdaspeed radiator and coil spring kit.
T4 rule book corrections #34437otherfasterT3 BMW 320i (14-15) gains aftermarket intercooler permission; T4 loses it.
T4 Ride Height Correction for the T3 Solstice. #34615wordingneutralT3 Pontiac Solstice GXP minimum ride height set to 3 inches.
FP Correct Intake Valve Size on 1500cc Midget/Spitfire #34419wordingneutralFP and HP Sprite, Midget, and Spitfire 1500 intake valve size corrected to 36.6/(1.44).
FP ITC to FP? #34286cars addedneutralHP Volkswagen Rabbit Cabriolet 1780 removed; Rabbit 1588 and 1715 reclassified with engine sizes and year ranges specified.
T2 370Z Obsolete Parts & NISMO Alternatives to SPL Parts #34297wordingneutralT2 Nissan 370Z allows NISMO suspension alternatives to SPL parts; rear toe arms removed from permitted list.
T4 2002-2006 Mini Cooper S R53 Spec Line Request #34336weight -50 lbsfasterT4 Mini Cooper S R53 loses 50 lbs, to 2700 for both 02-04 and 05-06 model years.
FP Request to Classify Sonic and Fiesta in HP #34264wordingneutralFord Fiesta HP and Chevrolet Sonic FP model year ranges extended from 2016 to 2019.
SRF3 Hoosier SRF Wet Front Tire Rule Update #34189tyres & wheelsunclearSRF Hoosier wet front tire updated to P/N 46100 P185/60R13 H20 or W2.
T2 2009 Porsche Cayman Classing Request #34147wordingneutralT2 Porsche Cayman S model year range extended from 06-08 to 06-09.
T4 05-06 Mini Wheel Weight #34112tyres & wheelsfasterT4 Mini Cooper S all years now run 17-inch wheels, up from 16, with wider rims to 8 inches.
T4 96-01 Audi a4 2.8 Spring Rate #34217suspension & brakesfasterT4 Audi A4 2.8 V6 wheels grow to 17x8, tyres to 245, springs now 800lb with 32mm sway bars.
FP Classification Request for 1978 Toyota Celica #34097cars addedneutral1978-80 Toyota Celica classified FP Prep Level 2, 2100-2205 lbs, 2190cc SOHC, 11.0:1 compression, .450" valve lift max.
SRF3 Update SRF Front W2 Rain Tire Part Number #34118tyres & wheelsneutralSRF Hoosier front rain tyre part number changes from 46100 to 46101 P185/65R13 W2.
T2 C5 Z06 Straight Line Speed #33575inductionslowerT2 Chevrolet Corvette C5 Z06 restrictor increases from 53mm to 56mm; 58mm option removed.
T2 Allowance of any nonmetallic bushing material in T2 #33833suspension & brakesneutralT2 upper and lower control arm bushings can now use polyurethane, delrin, or alternate synthetic materials.
T2 Allow Adjustable stabilizer bar links #33861suspension & brakesneutralT2 Cadillac CT4-V Blackwing now permits adjustable sway bar end links.
T4 Request to Classify 2004-2008 Acura TSX in T4 #33590cars addedneutralAcura TSX 2004-2008 newly classified in T4 at 3000 lbs minimum weight with 2354cc engine.
T4 T4 Mustang Brakes/Swaybar #34036suspension & brakesfasterT4 Mustang rear sway bar increases from 22mm to 28mm permitted.
SRF3 Update SRF Brake Rule #33469suspension & brakesslowerSRF Renault Alliance solid front rotors banned; restrictor reduced 35mm to 34mm for 2011+ Kawasaki; minimum weight increased to 1100 lbs for 2009+ stock engines.
SRF3 Update SRF Bodywork Fitment Rule #33765wordingneutralSRF3 tail sections allowed on SRFs with GEN3 airbox shimming up to 19 mm; alternate dash panel P/N 180100 or 180101 relocated in rules.
T2 Honda Civic Type R Tire Size Increase #33672tyres & wheelsfasterT2 Honda Civic Type-R tire size increases from 275 to 295.
T4 BMW 320I intercooler #33762otherfasterT3 BMW 320I now permitted to use aftermarket intercooler.
FP Request to Add Mazda Protege P5 to FP #33664wordingneutralFP Mazda Protégé ES (01-03) renamed to include P5 designation as Mazda Protégé ES/5 (01-03).
T4 Mustang OEM Grill Request #33333aeroneutralT2/T3 Mustang GT 5.0L and V6 (11-14) may remove upper grille fog lights, replace with mesh or screen.
T4 Mazda OEM LSD was letter 32655 typo #33666wordingneutralT4 Mazda MX-5 Club Model 06-15 Mazda Motorsports LSD part number corrected from 32655 to 0000-02-5564.
FP Review Limited Prep Port Matching Rules #33600wordingneutralEP, FP, HP cylinder head ports limited to 1 inch maximum depth matching from mating surface.
T2 BMW M235iR/M240iR Aftermarket 2WNR Shocks Allowed - Touring 2 #33464weight -50 lbsfasterT2 BMW M235iR weight reduced 50 lbs to 3350, aftermarket shocks now allowed.
T2 Touring (T2-T5) Category #33617cars addedneutralT5 class added as regional-only; T5 tyres maximum width 225, minimum aspect ratio 45.
T2 ENO 9.1.9.2.D.1.e.1.a. #33651suspension & brakesneutralT2-T5 Touring front and rear suspension maximum negative camber changed to 3.5 degrees.
T4 Allowable Springs and Sway Bars for 06-11 Civic si Spec Line #33294suspension & brakesfasterT4 Honda Civic Si 06-11 now permits 32mm sway bars front and rear and 700 pound springs.
T4 Touring (T2-T5) Category #33617cars addedneutralT5 class added as regional-only; T5 tyres maximum width 225, minimum aspect ratio 45.
T4 ENO 9.1.9.2.D.1.e.1.a. #33651suspension & brakesneutralT2-T5 Touring front and rear suspension maximum negative camber changed to 3.5 degrees.
T2 Heavy Cars #33345weight +125 lbsslowerT2 Dodge Viper SRT-10 wheel size 18x11 rear, weight to 3675 lbs, throttle restrictor hole 44mm convertible or 42mm hardtop.
T4 T4 mustang #32789tyres & wheels -25 lbsfasterT4 Ford Mustang V6 (05-10) wheels widen to 18x9, front brakes grow to 314mm vented, weight drops to 3275 lbs.
T4 Mazda OEM LSD was letter 32655 #32933weight -25 lbsfasterT4 Mazda MX-5 Club (06-15) minimum weight drops 25 lbs to 2600; Mazda LSD #32655 now permitted without penalty.
T4 Another 2022 BRZ/86 T3 request #32945weight +225 lbsslowerT3 Subaru BRZ 2022- minimum weight up to 2975 lbs; spring rate to 1000 F/R, brake parts allowed without penalty.
FP Request to classify VW New Beetle 2.5L in EP #32725cars addedneutralVW New Beetle 2.5L 5-cyl added to EP at 2400–2520 lbs, 2480 cc, fuel injection, comp ratio 12.0:1 max, valve lift 0.500" max.
FP Request Rotary Injection on Dual Y manifold #32775inductionunclearEP Mazda RX-7 12A/13B gains fuel injection option on dual-y manifold with 42mm choke(s).
FP Request for Corrado Stroke & Displacement Correction #32985wordingneutralEP VW Corrado 92-95 stroke corrected to 90.3 mm, displacement to 2792 cc.
FP Subaru BRZ Model Years #32500wordingneutralEP Subaru BRZ and Toyota 86/Scion FR-S model year ranges updated to 13-20.
SRF3 SRF Tire Rule Update #32614wordingneutralSRF tire rule wording changed from 'Tires: must be run as delivered' to 'Tires must be run as delivered.'
SRF3 Brake, seal, and air filter clarifications #32670suspension & brakesfasterSRF brake rotor minimum thickness reduced from 13.25 to 12.20mm; seal and air filter rules clarified.
T2 BMW M235iR/M240iR Min Weight Clarification #32430wordingfasterT2 BMW M235iR/M240iR: 240iR/Evo package now permitted without 50 lb penalty; Evo package clarified to 75 lbs.
T2 Follow up to Letter 30888 #32477suspension & brakesfasterT2 BMW E92 M3 (08-14) permitted to use Fall Line Suspension arms from G8X/F8x/E9x M3, E9x M3/E82 1M.
T4 Request Wider Wheels for Hyundai Tiburon #32536tyres & wheelsfasterT4 Hyundai Tiburon V-6 wheel width increases from 7 to 8 inches at 17-inch diameter.
FP Weight Adjustment of Lotus 7 #32213weight +50 lbsslowerFP Lotus Super Seven 91.7 ci minimum weight increases to 1580 lbs.
FP EP MX-5 Global Cup Car #32218weightslowerEP Mazda MX-5 Global Cup 16-22 minimum weight set to 2400 lbs; sequential gearbox allowed with +150 lbs penalty.
FP Please Class BMW 128i in EP #32370cars addedneutralBMW 128i (08-13) classified in EP at 2700 lbs minimum with stock throttle body, 11.0:1 compression ratio, 0.400 in. valve lift limits.
FP Inconsistency in Body Work Descriptions #32396aerofasterEP/FP/HP open cars may now use carbon fiber hardtops if they retain OEM appearance in all exterior profiles.
FP Request to classify the 1999-2000 Mazda Protege in FP #32398cars addedneutralMazda Protégé ES 99-00 classified in FP at 2150–2258 lbs with 1839cc DOHC engine, fuel injection, 11.0:1 compression, .450" valve lift limit.
T2 Request Alternate Front & Rear Strut/Shock Top Hats #32452suspension & brakesneutralT2-T4 Touring cars with alternative springs may use performance top hats with spherical bearings on shocks and struts.
T2 Request BoP E92 torque #32456wordingneutralT2 BMW E92 M3 (08-14) note reference changed from 77 to 78.
T2 Classify Cadillac Blackwing #32535cars addedneutralCadillac CT4-V Blackwing (2022+) classified in T2 at 3800 lbs with 94 x 85.6mm engine.
T4 Request to Add Spec Line for 2004-2009 Mazda3 i 2.0 #32395cars addedneutralT4 Mazda3 i 2.0L added as spec line with 1999cc displacement and 2425 lbs minimum weight.
T4 Request Alternate Front & Rear Strut/Shock Top Hats #32452suspension & brakesneutralT2-T4 Touring cars with alternative springs may use performance top hats with spherical bearings on shocks and struts.
FP Request Idle control valve clarification #32178wordingneutralEP and FP Production clarifies idle control valve rules: stock devices allowed original, removed with blocked ports, or mechanical replaced with electronic stock type.
FP Correct FP BMW 325e/es Displacement #32394wordingneutralFP BMW 325e/es displacement corrected from 1647 to 2693 cc.
T2 Request to Allow the Use of Aftermarket ECU's in Touring #31067weightslowerT2-T4 cars model year 2018+ may use non-OEM ECU with 75 lb weight penalty via spec line adjustment.
T2 BMW M2 CS Cup 2020- Exhaust #32243wordingunclearBMW M2 CS Cup 2020- now permits specific exhaust part #18302459928 and hot country package cooling parts.
T4 Request to Allow the Use of Aftermarket ECU's in Touring #31067weightslowerT2-T4 cars model year 2018+ may use non-OEM ECU with 75 lb weight penalty via spec line adjustment.
T4 Request JWT BSR Kit for 02-06 Nissan Sentra SE-R/Spec V #31685enginefasterT4 Nissan Sentra SE-R Spec V 02-06 now permits balance shaft removal kit OQR25-NOBAL.
T4 Please Confirm Touring 4 (98-00) BMW 323 is E46 generation #31972wordingunclearT4 BMW 323 (98-00) wheelbase increases to 2725 mm, final drive ratio changes to 3.07.
T4 RX-8 Spring Part Numbers (E&O) #32151suspension & brakesneutralT4 Mazda RX-8 04-12 gains Eibach spring alternatives to Mazda Motorsports springs front and rear.
T4 04-09 Mazda3 Tire Limit Clarification #32249tyres & wheelsfasterT4 Mazda3 04-09 tire size increases from 235 to 245.
T4 Shock Part Number Errors & Omissions #32252wordingneutralT4 Ford Mustang V6 05-10 shock part numbers corrected to 8741-1494SPORT front and 8241-1240SPORT rear.
T4 Update Solo Spec Coupe to latest '20 specs for Road Racing #32262wordingunclearT4 Scion FR-S and Subaru BRZ Solo Spec Coupes updated to 2020 specifications Rev 7/20.
T4 Request 2016 Mazda MX5 springs #32265suspension & brakesslowerT4 2016–18 Mazda MX-5 Miata/Club gains 100 lbs. for approved suspension package with specific springs.
FP EP Adjustments #31858inductionslowerEP BMW Z3 2.5L intake restrictor reduced from 59mm to 58mm flat plate.
FP 1999 3.8L Ford Mustang to EP? #31635weightfasterFord Mustang 99-03 classified to EP at 2700/2768/2835 lbs; 94-98 Mustang weight reduced to 2550/2614/2678 lbs.
FP Improved Touring Tires #32064tyres & wheelsneutralEP, FP, HP Improved Touring cars may use any DOT-approved tire per section 9.3.45 in Production class.
FP VW Golf Jetta 2.0L intake and exhaust size correction. #32173inductionslowerFP VW Golf III/Jetta III 93-98 intake valve to 39.5/1.56, exhaust to 32.9/1.30.
T2 Reply to letter #31486/29879 T2-T4 Grill openings #31935aerofasterT2-T4 grill openings may remove non-metallic webbed false sections; 16 square inch limit removed.
T2 C6 Restrictor Help #31995inductionfasterT2 Chevrolet Corvette C6 LS2 restrictor increases from 56mm to 58mm.
T4 Reply to letter #31486/29879 T2-T4 Grill openings #31935aerofasterT2-T4 grill openings may remove non-metallic webbed false sections; 16 square inch limit removed.
T4 BRZ vs BRZ TS #32022wordingneutralT3 Spec Lines Subaru BRZ TS (13-21) added to class specification wording.
FP Throttle Body and Idle Air #31800wordingneutralEP, FP, HP classes allow stock/original idle control devices unmodified or completely removed with openings blocked.
T2 BMW Z4M Adjustment #31885weight -50 lbsfasterT2 BMW Z4M 06-08 weight reduced from 3150 to 3100 lbs.
T4 MX-5 Durability Detailed #31102weightslowerT4 Mazda MX-5 Club 06-15 allows non-OEM LSD with +50 lbs penalty; removes stock transmission and differential requirements.
T4 Request Allowances for 2005 - 2010 Mustang #31624suspension & brakesneutralT4 2005-2010 Ford Mustang V6 now specifies Koni damper part numbers 8741.1494 front and 8741.1240 rear.
FP Porsche 968 Engine Questions #31478enginefasterEP Porsche 968 intake valve size increased from 37 to 39.0 mm.
FP PCS E. 2. n. 4. Add Axle Shaft to Allow FWD the Same Freedom #31592wordingneutralEP, FP, HP front-wheel-drive cars may alter body and suspension to install alternate transmission, transaxle, and axle shaft.
FP BMW Z3 2.5L Spec Line #31724wordingneutralEP BMW Z3 2.5L allows alternate throttle body from 92-95 325i with Turner adapter; head casting 1738400 permitted with specific blocks.
FP FP Del Sol VTEC #31859enginefasterFP Honda Civic Del Sol VTEC removes restrictions on dry sump, connecting rods, intake manifold porting, crankshaft, rocker arms, cam followers.
FP Standardize Level 2 Classifications in FP #31868wordingneutralFP Honda Prelude 84-87 and Mazda GLC/323 86-88 standardize valve lift measurement and remove Level 1 dry sump restrictions.
T2 Touring 2 BOP adjustments for 2022 #31480weight -50 lbsfasterT2 Dodge Viper SRT-10 loses 50 lbs to 3550; throttle restrictor hole shrinks from 43mm to 41mm.
T2 Reply to letter 29879 T2-T4 Grill Openings #31486aerofasterT2-T4 clarified: grill opening area may increase max 16 sq in for radiator cooling only, retaining factory mesh shape.
T2 Request to clarify radiator hoses #31682wordingneutralT2, T3, T4 radiator and coolant hoses may be replaced with aftermarket options; coolant temp sensor modification permitted.
T2 Clarify Permitted/Allowed #31743wordingneutralT2, T3, T4 clarify that spec lines listing permitted or allowed parts are alternatives to category rules, not replacements.
T2 SMG #31837wordingneutralT2 Spec Mustang model designation changed to Ford Spec Mustang.
T4 Reply to letter 29879 T2-T4 Grill Openings #31486aerofasterT2-T4 clarified: grill opening area may increase max 16 sq in for radiator cooling only, retaining factory mesh shape.
T4 Please Adjust 98-00 BMW 323 Min Weight to Reflect Current Class #31595weight -200 lbsfasterT4 BMW 323 98-00 minimum weight drops to 3250 lbs, 50mm restrictor removed.
T4 Consolidate 12-13 and 14-15 Honda Civic Si spec lines for T4 #31596wordingneutralT4 Honda Civic Si consolidates 12-13 and 14-15 into single 12-15 spec line with updated suspension allowances.
T4 Request to clarify radiator hoses #31682wordingneutralT2, T3, T4 radiator and coolant hoses may be replaced with aftermarket options; coolant temp sensor modification permitted.
T4 Clarify Permitted/Allowed #31743wordingneutralT2, T3, T4 clarify that spec lines listing permitted or allowed parts are alternatives to category rules, not replacements.
T4 Correct RSX wording #31746wordingfasterT4 Acura RSX/RSX Type-S 02-06 removes requirement that original wheels must remain stock.
T4 Camaro #31751suspension & brakesfasterT4 Chevrolet Camaro V-6 (96-02) removes requirement that shock/struts, mounts, and transmission differential remain stock.
FP 944S2 Restrictor #31396inductionslowerEP Porsche 944S2 89-91 requires 56mm flat plate intake restrictor; comp ratio max 12.0:1, valve lift max 0.500".
FP Classing Clarification for 1986 Toyota Corolla FX16 #31527cars addedneutralHP Corolla GTS RWD (84-87) added at 2300 lbs; HP Corolla FX16 FWD (87-88) added at 2260 lbs; old Corolla (84-87) removed.
SRF3 Three Updates to SRF Rules #31523tyres & wheelsunclearSRF front wet tire changes from P185/60R13 H20 to P185/65R13 W2; SRF3 adds mandatory G301048 restrictor plate Jan. 1, 2022.
T2 Typo for BMW M2 CS Cup 2020 #31173suspension & brakesslowerT2 BMW M2 CS Cup 2020 rear brake rotor reduced from 390 mm to 380 mm.
T4 Nissan Sentra SE-R Spec. V #30958cars addedneutralNissan Sentra SE-R Spec V (2007–2012) newly classified in T4 at 3000 lbs minimum weight.
T4 Mazda RX-8 Spec Line Suspension Parts #31113suspension & brakesfasterT4 Mazda RX-8 04-12 allows alternate sway bars max 32mm front, 19mm rear; removes 60mm restrictor requirement.
T4 Diverter Valve Plunger Upgrade #31307wordingneutralT4 BMW 320i (14-15) now allows GFB T9357 aluminum diverter valve.
T4 Adjust Honda FWD in T4 to encourage more Drivetrain Diversity #31472tyres & wheelsfasterT4 Honda Civic FWD gets wider 8-inch wheels, 245 tyres max, and sway bar allowances to 29mm front, 22mm rear.
T4 Touring 4 BOP adjustments for 2022 #31482weight -175 lbsslowerT4 multiple cars: Volkswagen Rabbit 2.5 (08-09) to 2675 lbs; Mazda MX-5/Club (06-15) to 2625 lbs; RX-8 to 3125 lbs; Honda/Acura/Chevy/Mazda wheel widths 7 to 8 inches.
T2 Request to Classify 2014 VW Jetta 1.8t TSI #30436cars addedneutralT4 Volkswagen Passat, Jetta 1.8T adds 2014 model year to eligible years.
T2 Request new car 2017 BMW M2 #30486cars addedneutralBMW M2 (2017+) added to T2 with 2979cc engine, 10.5x18 wheels, 295 tires, 3650 lbs weight.
T2 Request to Classify Porsche 997.2 GTS in T2 (body not = to C2S) #30686cars addedneutralPorsche 911 997.2 GTS (09-12) classified in T2 at 3400 lbs with 60mm flat plate restrictor required.
T4 Request to Classify 2014 VW Jetta 1.8t TSI #30436cars addedneutralT4 Volkswagen Passat, Jetta 1.8T adds 2014 model year to eligible years.
FP E&O; MR2 Track #31120wordingneutralHP Toyota MR-2 1.6L (85-89) track corrected to 15.47 inches front and rear.
T2 BMW M2 CS Power Stick Part Number #31087wordingneutralT2 BMW M2 CS Cup 2020- must run Purple power stick, part #8324089 instead of #TBD.
FP Request to Allow F22c Engine for 2000-2003 Honda S2000 #30548cars addedunclearHonda S2000 (00-03) reclassified as EP Prep with F22c engine option: 1997cc or 2157cc, weight 2450–2636 lbs depending on displacement.
FP Request a review of the S14 240SX in EP. #30873weight -200 lbsfasterEP Nissan 240-SX S13/S14 loses 200-210 lbs minimum weight; comp ratio rises to 12.0:1, valve lift to .500.
SRF3 SRF Wet Tires #30849tyres & wheelsneutralSRF wet tyres add Hoosier P185/60R13 W2 front and P205/60R13 W2 rear as alternatives to H20.
SRF3 SADEV-SRF3 Transmission #30926cars addedunclearSRF adds SADEV-SRF3 6-speed sequential option with final drive 3.20 versus OEM 5-speed 3.85.
SRF3 SRF Update Maintenance, Repairs and Seals #30961wordingneutralSRF seal procedures clarified: unsealed components need CSR inspection and logbook notation instead of engine removal.
T2 997.1 EO #30933wordingneutralT2 Porsche 911/997.1 (06-08) now allows alternate Cargraphics CARP97DFIFKR exhaust manifold.
FP Lotus/Caterham 7 America Request #30392wordingunclearEP Lotus/Caterham 7 America carburetor changed from IT fuel injection prep to fuel injection.
FP Request to classify ITC Plymouth Arrow #30588cars addedneutralPlymouth Arrow 1598cc four-cylinder classified to HP at 1800 lbs minimum weight.
FP Reclassification of the 1984/85 BMW 318i from FP to HP #30661cars addedneutralBMW 318i E30 (84-85) reclassified from FP to HP at 2200–2310 lbs with fuel injection and .425" valve lift limit.
FP Fiat x1/9 Competition Adjustments #30711weight -50 lbsfasterFP Fiat X-1/9 1300 loses 50 lbs to 1665; X-1/9 loses 50 lbs to 1765.
FP Reclassify Daimler SP 250 #30721cars addedneutralDaimler SP 250 classified in EP at 2165 lbs with 2548 cc OHV 8-cylinder engine.
T2 Request #30406weightfasterT2 BMW M2 CS Cup 2020- weight increases from 3625 to 3600 lbs; mandatory Purple power stick added.
T4 Wrong Part Number on 320i Spec Line #30645wordingneutralT4 BMW 320i 14-15 part number corrected from 20121.140 to E10-20-031-01-22.
FP Move Porsche 924 in Level 1 Prep From EP to FP #30135cars addedneutralPorsche 924 moves from EP to FP Level 1 Prep, classified at 2200 lbs with 1984cc 4-cylinder OHC engine.
FP Clarify Application of Percentage Based Weight Penalties #30669weightslowerEP, FP, HP clarifies percentage weight penalties sum first, then apply to base weight, rounding to nearest pound.
SRF3 SRF3 Alternator Pulley #30684engineslowerSRF3 alternator pulley restricted to P/N G902130 or G902130A, 12oz minimum weight.
T2 Civic Type R Brake Rotors #29817weightslowerT3 Honda Civic Type-R 2020+ allows brake rotor 45251-TGH-A01 with 25 lb penalty.
T2 Mustang S550 Parity in T2 #29925inductionfasterT2 Ford Mustang GT 5.0L 15-17 restrictor grows 55mm to 58mm; 2018- grows 53mm to 55mm.
T2 Request BOP on BMW Z4 T2 car #30597weight +50 lbsslowerT2 BMW Z4M 06-08 weight increases from 3100 to 3150 lbs.
T2 E92 #30639weight -50 lbsfasterT2 BMW E92M3 08-14 weight drops 50 lbs to 3425, intake restrictor reduces 3mm to 77mm.
T4 Civic Type R Brake Rotors #29817weightslowerT3 Honda Civic Type-R 2020+ allows brake rotor 45251-TGH-A01 with 25 lb penalty.
FP Change Classification of 84-87 Mazda 626 from FP to HP #30350cars addedneutral84-87 Mazda 626 reclassified from FP to HP with 2300–2415 lbs weight, 1998cc SOHC, dual 32mm carbs.
FP Fiat X1/9 brake rotors #30423suspension & brakesneutralFP Fiat X1/9 brake rotors change to 257 (10.1) x 12 (.407) solid disc.
T2 C5/6 Corvette in T1, T1-LP and T2 Dry Sump Standardization #29046wordingneutralT2 C5 and C6 Corvettes permit specific dry sump kits and minor air dam trimming up to 3.9 cm depth.
T2 Request for Chevrolet Camaro 1LE (2016-) Auto Trans #29067wordingunclearT2 Chevrolet Camaro 1LE auto trans gets new gear ratios and 2.77 final drive ratio.
T2 Request to add 2015 to Chevrolet Camaro SS/1LE 2010-2014 #29736cars addedneutralT2 Chevrolet Camaro SS/1LE model years expanded from 2010–2014 to 2010–2015.
T4 Mini Cooper Spec Line Anomalies #30478suspension & brakesunclearT4 Mini Cooper S (02-04, 05-06) suspension/wheel rules simplified; (07-13) gear ratios changed to 3.31, 2.13, 1.48, 1.14, 0.95, 0.82, final drive to 3.65, brakes to 280 mm.
T4 Request CAI Mustang in T4 #30562inductionfasterT4 Ford Mustang V6 05-10 now allows cold air intake.
FP Please Classify Mazda3 in FP #30165cars addedneutralMazda 3 S 04-08 classified in EP at 2350 lbs minimum, 2.26L DOHC, 12.0:1 compression, .500" valve lift limit.
FP Golf MkIII Valve Size Request #30268enginefasterFP Volkswagen Golf III and IV intake valves increase to 40.0 mm, exhaust valves to 33.0 mm.
T2 Request consistency review in GCR #30263wordingslowerT2-T4 clutch disc and pressure plate must be at least 95% of factory OEM weight.
T2 Class Spec Corvette in T2? #30297cars addedneutralSpec Corvette newly classified in T2 at 3375 lbs with 53mm restrictor and 3.75" minimum ride height required.
T2 E92 BMW Spring Rate Request #30391suspension & brakesfasterT2 BMW E92 M3 front and rear springs increased to 1000 lbs/in from 800.
T2 Please correct recent T2 Spec Line #30401suspension & brakesneutralT2 Toyota Supra 2020- spring rates limited to 800# front and 1000# rear maximum.
T4 Request consistency review in GCR #30263wordingslowerT2-T4 clutch disc and pressure plate must be at least 95% of factory OEM weight.
SRF3 Mandatory identification: #30223wordingneutralSRF and SRF3 mandatory identification simplified: removed Ford Performance and Blue Oval decals, kept Hoosier logo placement.
T2 Request BMW M2CS door glass removal #30254aerofasterT2 BMW M2 CS Cup 2020- permitted to remove door glass and mechanism.
T4 E & O T4 Mustang Wheels #30245tyres & wheelsfasterT4 Ford Mustang V6 05-10 wheels increase from 17 to 18 inches.
T2 Request Addition of BMW M240iR #29503cars addedslowerT2 BMW M235iR allows 240iR/Evo package with 50 lb penalty, must run DOT tires.
T2 2021 Toyota Supra #29567cars addedneutralToyota Supra 2020- newly classified in T2 at 3450 lbs minimum weight with 295 tire and 19-inch wheels.
T2 Request Cold Air Intake for Honda Civic Type R #29942wordingneutralT2 Honda Civic Type-R gains allowance for PRL cold air intake #PRL PRL-HCR-INT-HVI.
T2 Adjust T2 spec line that was missed in T2 BOP #30055weight -50 lbsfasterT2 Porsche Carrera S 997.2 (06-08) weight reduced 50 lbs to 3225.
T2 Fix T2 Mustang spec line #30106wordingneutralT2 Ford Mustang GT 5.0L (15-17) gear ratios corrected to 3.66, 2.43, 1.69, 1.32, 1.00, 0.65 or 4.17, 2.34, 1.52, 1.14, 0.87, 0.69.
T2 Z4 Wheel Size #30113tyres & wheelsfasterT2 BMW Z4M 06-08 maximum wheel size increases from 18x9 to 18x10 inches.
T2 Clarify T2 Spec lines #30194wordingneutralT2 BMW M2 CS Cup 2020- and M235iR clarify homologation notes for DOT tires and BMW Motorsports components.
T4 2021 Toyota Supra #29567cars addedneutralToyota Supra 2020- newly classified in T2 at 3450 lbs minimum weight with 295 tire and 19-inch wheels.
T4 06-15 MX-5 Durability #29781wordingneutralT4 Mazda MX-5 durability rule now applies to T2-T4 instead of T2-T3 only.
T4 Request for Update to T4 Spec Line for Chevrolet Sonic (2011-) #29838wordingneutralT4 Chevrolet Sonic (2011-) spec clarified: 28mm TIR restrictor placement, PCV plug requirement, and allowed suspension parts listed.
T4 NC MX-5 06-15 Part Number updates for 2021 #29921wordingneutralT4 Mazda MX-5 06-15 removes front and rear end links from suspension package spec.
T4 BMW Z4 2.5L (03-05) Spec Line #30037weight -50 lbsfasterT4 BMW Z4 2.5L (03-05) minimum weight reduced from 3100 to 3050 lbs.
T4 Sway Bars for T4 2016+ MX5 Mazda #30063suspension & brakesneutralT4 2016+ Mazda MX-5 Miata gains allowance for 29mm front and 16mm rear sway bars.
T4 Change part numbers on BRZ, FRS lines in T4 #30104wordingneutralT4 Scion FR-S, Subaru BRZ, and Toyota 86 replace Eibach part 4.10582.880 with 82105.320, 4.10582 and SPC 67660.
T4 T4 Mustang Axle Ratio and Wheels #30149weightslowerT4 Ford Mustang V6 05-10 allows GT 8.8 rear axle with 3.45 or 3.55 ratio at +25 lb penalty.
FP Alternate Front Brake Rotors and Calipers for EP AH 3000 #29893suspension & brakesneutralEP Austin-Healey 3000 Mk. I, II, III now allows TR-6 front calipers and discs as alternate.
T2 Request to Classify BMW M2 CS #29523cars addedneutralBMW M2 CS Cup 2020+ classified in T2 at 3625 lbs with 2979cc engine, 10.5x18 wheels, 295 tires.
T2 350Z Rear Caliper Replacement #29710wordingneutralT2 and T3 Nissan 350Z and 370Z permit 44011-RC350 rear caliper kit and SZ350 rotors.
T2 Request Mustang 8.8†rear axle replacement #29860weightslowerT4 Ford Mustang V6 05-10 allows GT 8.8 rear axle with 3.55 final drive, adds 25 lb penalty.
T2 Cap year range on all 86s #29908wordingneutralT3 and T4 FR-S, 86, and BRZ year ranges capped: T3 at 2021, T4 at 2017-2021.
T4 Request to Classify BMW M2 CS #29523cars addedneutralBMW M2 CS Cup 2020+ classified in T2 at 3625 lbs with 2979cc engine, 10.5x18 wheels, 295 tires.
T4 Allow the SpecMX-5 Update Kit Into Touring 4 for the MX-5 #29681wordingunclearT3 and T4 Mazda MX-5 06-15 now allow Mazda Transmission kit part # 0000-02-5700.
T4 Request Mustang 8.8†rear axle replacement #29860weightslowerT4 Ford Mustang V6 05-10 allows GT 8.8 rear axle with 3.55 final drive, adds 25 lb penalty.
T4 Cap year range on all 86s #29908wordingneutralT3 and T4 FR-S, 86, and BRZ year ranges capped: T3 at 2021, T4 at 2017-2021.
FP Mk2 VW Consistency and Cleanup of FP and HP Spec Lines #29195weight -50 lbsfasterFP Volkswagen Golf and Jetta 1.8 lose 50 lbs each, to 1900. HP Jetta GLI engine code removed.
FP Correct Wording for Level 1 and Level 2 Induction Systems #29406wordingneutralEP, FP, HP Level 1 and Level 2 induction systems: clarified carburetor and fuel injection rules, jets/needles/rods unrestricted in Level 2.
FP Weight Reduction for Datsun Roadster #29409weight -75 lbsfasterEP Datsun SRL 311U Roadster minimum weight reduced to 1925 lbs from 2000 lbs.
FP EP TR8 Adjustment #29512weight -100 lbsfasterEP Triumph TR8 78-81 weight reduced from 2600 to 2500 lbs.
FP Request to Classify 1996-2000 Honda Civic EX #29515cars addedneutralHonda Civic EX 96-00 classified in FP at 1975 lbs, 1590cc SOHC, 56mm throttle body, valve lift .450" max.
FP FAJS Carburetor #29576wordingneutralFP adds FAJS carburetor to permitted Weber and auto-type substitutions in two rule sections.
SRF3 SRF Shocks, Springs and Ride Height. #29688suspension & brakesneutralSRF shocks, springs, bump stops sealed; rear springs 412-429 lbs/in P/N 280390 only; previous parts no longer allowed.
T2 Request to Reevaluate T2 Spec Line for E92 M3 #28266weight -50 lbsfasterT2 BMW E92 M3 (08-14) weight reduced 50 lbs to 3475, with detailed brake, spring, sway bar, and restrictor specs.
T2 Request for Parity Among Vehicles Including S550 Mustang #29486induction -75 lbsfasterT2 Corvette C5 Z06 restrictor sizes increase to 53mm and 58mm; C6 LS2 to 56mm, LS3 to 50mm; Camaro SS/1LE weight drops 75 lbs to 3625; 2016+ Camaro restrictor to 56mm; Mustang GT 11-14 to 58mm, 15-17 to 55mm, 2018+ to 53mm; Viper SRT-10 th…
T2 Alfa Romeo 4C Launch Edition #29531wordingneutralT3 Alfa Romeo 4C Launch Edition now allowed in Spec Lines.
T4 Alfa Romeo 4C Launch Edition #29531wordingneutralT3 Alfa Romeo 4C Launch Edition now allowed in Spec Lines.
T4 Post Runoffs Feedback for T4 #29752tyres & wheels -50 lbs
FP 84-87 Toyota Corolla HP Wheel Diameter Allowance Proposal E&O #29458tyres & wheelsfasterHP 84-87 Toyota Corolla wheel diameter increases from 13 to 15 inches.
T2 Request 2018+ mustang swaybar update #28659wordingneutralT2 Ford Mustang GT 5.0L and Ecoboost 2.3 sway bar part numbers added to notes.
T2 Request to Clarify New 2-piece Brake Rotor Rule #29106wordingneutralT2 brake rotors expand from ferrous metal only to 2-piece ferrous disks with aluminum hats, within 5% OE diameter.
T2 please consider BoP for the following cars in T2 #29266weight -50 lbsfasterT2 Corvette C-5 Z06 loses 50 lbs to 3425; Camaro SS/1LE loses 50 lbs to 3650; Mustang GT and Boss 302 gain 275 to 295 tyres.
T2 Request clarification on most recent approval by the Board #29284wordingneutralT2 Porsche Cayman S, Spyder (10-12) allows 800#/in front and 1000#/in rear springs, cooler ducting, rotor ducting, and specific Porsche and StopTech brake items.
FP EP BMW Z3 Rule Clarification #28998wordingneutralEP BMW Z3 2.5L iron block casting 1738566-C designation removed, wording clarification only.
T2 Request to correct GCR for 2018+ FORD Mustang GT & Ecoboost #28803wordingneutralT2 Ford Mustang EcoBoost and GT 5.0L gain three optional gear ratio sets for competition use.
T4 Scion FRS Solo Spec Coupe Gear Ratio #29021otherfasterT4 Scion FRS and Subaru BRZ Solo Spec Coupe final drive ratio changed from 4.30 to 4.10.
FP Request to Classify Porsche 911 2.0L #28456cars addedneutralPorsche 911 S 67-68 classified in EP at three weight levels: 1800, 1845, or 1890 lbs.
FP Request to change to Carburetor Spec Line 84-87 Mazda 626 #28926wordingunclearFP Mazda 626 84-87 carburetor spec now specifies two auto-type sidedraft 32mm choke carbs or fuel injection.
T2 Request to Add a Vehicle to the Roster (contd.) #27698cars addedunclearCannot read: letter references external document #27663 not provided.
T2 Request brake upgrade and electric power steering pump #28946suspension & brakesfasterT2 Porsche Cayman S, Spyder (10-12) gains brake, suspension, and drivetrain upgrades: StopTech calipers, 800#/in front and 1000#/in rear springs, Porsche control arms, PDK allowed.
T4 T4 RX8 bodywork clarification #28941aeroneutralT4 Mazda RX-8 04-12 now allows OE rear spoiler #F151-V4-920F and OE front air dam #F151-V4-900f-BB.
T4 2006-2015 MX-5 Clarification #28942otherfasterT4 2006-2015 Mazda MX-5 Club Model now allows non-stock wheels; transmission, differential, LSD remain stock.
T4 Request to Add a Vehicle to the Roster (contd.) #27698cars addedunclearCannot read: letter references external document #27663 not provided.
FP BMW Cylinder Head Casting and Part Numbers #28708engineslowerEP BMW 2.8L, 328i E36/E46, and 325i E36 blocks now iron only; 325i E46 aluminum only.
FP Correct Scirocco Spec line E&O #28892cars addedneutralFP Volkswagen Scirocco E&O adds four engine variants with weights 1520–1853 lbs and displacements 1471–1780 cc.
SRF3 SRF Shocks #28791wordingneutralSRF3 shock absorber brand restriction removed; all shocks must be sealed by Enterprises.
T2 Request to Classify 2004 Mercedes Benz 320 CLK #27663cars addedneutral2004 Mercedes Benz CLK 320 Coupe classified in T4 at 3200 lbs with 3299cc engine and Eibach PN# 2563.140 springs allowed.
T2 Consider coil spring conversion Corvette in T2 #28824suspension & brakesneutralT1 and T2 Corvettes may convert leaf spring suspension to coilover with 800 lb max spring rate allowed.
T4 Request to Classify 2004 Mercedes Benz 320 CLK #27663cars addedneutral2004 Mercedes Benz CLK 320 Coupe classified in T4 at 3200 lbs with 3299cc engine and Eibach PN# 2563.140 springs allowed.
FP Request to Classify 1990-1994 Mazda Protege #28381cars addedneutral1990-1994 Mazda Protege classified in FP Pre at 2150–2258 lbs with 1839cc DOHC engine, fuel injection.
FP Error in Mini Cooper Spec Line #28713wordingneutralHP Mini Cooper model year ranges for convertibles revised: 02-06 now includes 05-08, 07-13 now includes 09-15.
SRF3 Update Bump Stop Rule #28712suspension & brakesneutralSRF3 bump stop now must be SCCA P/N 280407 only, no modifications, optional, max one per shock.
SRF3 SRF Bump Stop Correction #27019wordingneutralSRF shock absorber bump stop clarified: only SCCA P/N 280407 allowed as delivered, maximum one per shock, effective 05/01/2020.
T2 Please Add the Following BBK to Allowed List for E92 M3 #28421suspension & brakesneutralT2 BMW E92 M3 08-14 gains approved AP Racing brake kit part numbers 13.01.10038 front, 13.01.10053 rear.
T2 C5 Weight Adjustment #28433weight -50 lbsfasterT2 Chevrolet Corvette C5 Z06 loses 50 lbs with 45mm restrictor, to 3175; 50 lbs with 55mm restrictor, to 3350.
T2 Z3M Roadster Weight #28437weightfasterT3 BMW Z3 M & Coupe 1998-1999 weight reduced from 3350 to 3150 lbs.
T4 Request to change allowed header part # for T4 06-15 Miata #28223wordingneutralT4 06-15 Mazda MX-5 now allows header part numbers 0000-06-5407 or 0000-06-5407-NC.
T4 Z3M Roadster Weight #28437weightfasterT3 BMW Z3 M & Coupe 1998-1999 weight reduced from 3350 to 3150 lbs.
FP Caterham 7 Spec Line #28498wordingneutralEP Caterham 7 Spec Line removes redundant suspension note, clarifies engine prep limits and comp ratio to 10.0:1.
FP Request to classify SOHC 1989-90 240SX in F prod L2 #28553cars addedneutral1989-90 Nissan 240-SX SOHC added to FP Level 2 with 2400-2520 lbs weight range.
T2 Limit Changes to the 997.2 Porsche #28242aeroslowerT2 Porsche 911 997.2 allows GT3 Cup front fascia with 75 lb penalty; OEM rear deck lid and GT3 Cup splitter now required or prohibited.
T2 Correct T2 Mustang Transmission #28732wordingunclearT2 Ford Mustang GT 5.0L 15-17 transmission gear ratios corrected to two allowed options.
FP Request to allow 40 DCOE carb for the Datsun 510 #28195inductionfasterHP Datsun 510 gains 40 DCOE carburetor option alongside existing 40 DCN and 36mm DCNVH choices.
FP Request to classify Porsche 914 2L in LPrep FProd #28231cars addedneutralPorsche 914-4 2.0L classified in FP Prep 2 at 2030-2132 lbs with 1968cc OHV engine, 11.0:1 compression limit, .450" valve lift limit.
FP Request Ford Fiesta Weight Adjustment #28336weightfasterFP Ford Fiesta 78-80 weight reduced 130 lbs to 1660.
T2 Request to Readjust the T2 Porsches #27746aeroslowerT2 Porsche 911/997 (06-08, 09-12, Carrera S 06-08) aero rules relaxed; 997.2 adds 60mm restrictor and PDK +100lbs option.
T4 Request for 12-13 and 14-15 Honda Civic Springs #27848wordingneutralT4 Honda Civic Si 12-13 and 14-15 now allow H&R and HPD springs up to 700 pounds with 47mm restrictor.
T4 Request to Clarify T4 05-10 Mustang Spring Allowance #27899suspension & brakesneutralT4 Ford Mustang V6 05-10 springs now permitted max 500 lbs front and 400 lbs rear.
FP Request for Help for Datsun 1200 #27934inductionfasterHP Datsun 1200 carburetor choke size increases from 26mm to 30mm.
T2 Please Switch the Solstice GXP as Specified in T2, to T3 #27413cars added -50 lbsfasterPontiac Solstice GXP and Saturn Sky move from T2 to T3; wheels widen to 18 x 9.5 inches, Sky weight drops to 3200 lbs.
T2 Request for Two Piece Stop Tech Brake Rotors #27582otherneutralT2 cars now allowed to use ferrous metal 2-piece brake rotors within 5% of OE diameter.
T2 Request to Classify all Mazda RX8 Models in T3/T4 #27606cars addedneutralMazda RX-8 Base/R3/Sport/GT (04-12) classified in T3 effective 2020-02-01.
T2 Request for Alternative Brake Kit on Nissan 370Z #27912suspension & brakesslowerT2 Nissan 370Z gains alternative Stoptech brake kit option with 50 lb weight penalty.
T2 2015- Current Ecoboost Mustang #27971weight -100 lbsfasterT2 Ford Mustang Ecoboost 2.3 loses 100 lbs to 3400, wheels widen to 19 x 11, intercooler TIR increases to 50mm.
T4 Request to Allow Brake Upgrade on T4 Mustang #27329otherneutralT4 Ford Mustang V6 05-10 allowed aluminum driveshaft, any LSD, and Ford brake kit M-2300-D.
T4 Please Switch the Solstice GXP as Specified in T2, to T3 #27413cars added -50 lbsfasterPontiac Solstice GXP and Saturn Sky move from T2 to T3; wheels widen to 18 x 9.5 inches, Sky weight drops to 3200 lbs.
T4 Request to Classify all Mazda RX8 Models in T3/T4 #27606cars addedneutralMazda RX-8 Base/R3/Sport/GT (04-12) classified in T3 effective 2020-02-01.
T4 Request for 2014-2018 Mazda 3 GT Brakes #27659suspension & brakesfasterT4 Mazda3 14-18 gains permitted modifications: springs to 800/1000 lbs, 15 lb wheels, cold air intake, camber plates, 25mm rear bar, mirrors, CorkSport arms, header, specific calipers and rotor.
T4 Request to allow aftermarket OEM coolant expansion tank #27763wordingneutralT4 allows aftermarket OEM coolant expansion tanks with no other functional purpose.
T4 Request to allow aftermarket OEM power steering reservoir #27764wordingneutralT4 Mazda MX-5 Club Model 06-15 now allows aftermarket power steering reservoir.
T4 Request for Factory Installed Wings on Subaru BRZ #27831wordingneutralT4 Subaru BRZ and Scion FR-S allowed factory installed wings.
T4 Request for Replacement Clutches #27892wordingneutralT4 now permitted to use any OEM diameter clutch disc and pressure plate, previously T2-T3 only.
T4 Request to Classify Chevy Sonic 1.4 In T4 #27906cars addedneutralChevrolet Sonic 2011+ added to T4 at 2800 lbs with 1364 cc engine and 225 max tire size.
FP Request to List Mazda Miata Throttle Body Size #27907wordingneutralFP and EP Mazda Miata models standardized to 55mm throttle body diameter; brake spec clarified.
FP Request to Classify 2001-2003 Mazda Protege ES in FP #27922cars addedneutralFP Mazda Protégé ES 01-03 newly classified at 2350–2468 lbs with 1991cc 4-cyl DOHC, fuel injection, 11.0:1 compression, .450 in. valve lift limit.
T2 Clarification of On-Board Fire System for T2 #27183wordingneutralT2 requires onboard fire system; T3 and T4 may have one per GCR 9.3.
T2 Mustang Ecoboost and GT Transmission #27439otherunclearT3 Ford Mustang EcoBoost 2015- gains three transmission gear ratio options.
T2 Request for Dailey Engineering Dry Sump on 2010 Camaro SS #27514otherneutralT2 Chevrolet Camaro SS/1LE (10-14) adds Dailey Engineering dry sump P/N 20-02-0666-ASSY and other approved parts.
T2 Request for Half Shafts - 2014 Camaro SS 1LE #27584otherneutralT2 Camaro SS 1LE gains approval for half shafts Drive Shaft Shop RA-5424 and RA-5425.
T2 Request for Parity Among Vehicles #27665induction -50 lbsfasterT2 Ford Mustang Boss 302 restrictor 54mm to 56mm; GT 5.0L 11-14 restrictor 52mm to 54mm; GT 5.0L 15-17 restrictor 50mm to 52mm; C5 Z06 weight 3525 to 3475 lbs; C6 weight 3450 to 3400 lbs; Porsche 911 997.2 restrictor 60mm to 57mm.
T2 Request for 2016-2020 Camaro SS Help #27776weight -50 lbsfasterT2 Chevrolet Camaro 1LE 2016- weight reduced from 3600 to 3550 lbs.
T2 Request for Competitive Adjustments to Honda Civic Type R #27839weight -50 lbsfasterT2 Honda Civic Type-R (2017-) weight reduced from 3050 to 3000 lbs; tire TIR requirement increased from 50mm to 51mm.
T2 T4 RX8 Classification Error #27902wordingneutralMazda RX-8 Base/R3 (04-12) reclassified in T3 and T4 to include Sport and GT variants.
T2 Request to add Toyota 86 GT to Spec Line #27910cars addedneutralToyota 86 GT (2017-) added to T3 and T4 Spec Line.
T4 Clarification of On-Board Fire System for T2 #27183wordingneutralT2 requires onboard fire system; T3 and T4 may have one per GCR 9.3.
T4 Mustang Ecoboost and GT Transmission #27439otherunclearT3 Ford Mustang EcoBoost 2015- gains three transmission gear ratio options.
T4 BRZ/FRS/86 Tire Size in T4 #27660tyres & wheelsslowerT4 BRZ, FR-S, and 86 maximum tire size reduced from 245 to 225.
T4 NC MX5 2006-2015 Spec Adjustment Request #27739weight -75 lbsfasterT4 Mazda MX-5 Club Model 06-15 minimum weight cut from 2625 to 2550 lbs.
T4 T4 RX8 Classification Error #27902wordingneutralMazda RX-8 Base/R3 (04-12) reclassified in T3 and T4 to include Sport and GT variants.
T4 Request to add Toyota 86 GT to Spec Line #27910cars addedneutralToyota 86 GT (2017-) added to T3 and T4 Spec Line.
SRF3 SRF Rain / Brake Rule - BoD approved as follows #34958wordingneutralSRF rain and brake rule wording updated; supersedes GCR 9.3.32.B.2 effective 1/1/202 through 12/31/2024.
FP Request to Correct Track of 1988-91 Honda Civic #27487wordingneutralFP and HP Honda Civic and CRX 1988–91 track specifications corrected to 61.3/61.7 inches.
FP Re-organize Prep2 Cylinder Head Rules for Clarity & Consistency #27661wordingneutralEP, FP, HP cylinder head rules reorganized for clarity; no performance change.
SRF3 SRF Tire Warmer Rule #27622tyres & wheelsslowerSRF bans tire warmers and cooling methods other than natural air convection or conduction.
SRF3 SRF / SRF3 Nose Weight Reduction #27706weightfasterSRF front nose weight minimum reduced from 35 to 32 lbs.
SRF3 SRF / SRF3 Majors & Regional Class Updates #27723wordingneutralSRF3 reclassified as Spec Racer Ford 3 with 1.6L conversion; SRF2 becomes Regional Only Class.
FP Request bodywork for Austin Healey Bugeye Sprite MK1 #27106wordingneutralFP and HP Austin-Healey Sprite Mk I and MG Midget variants may replace rear bodywork aft of cockpit with stock-appearing alternate material components.
FP Request to classify the GMX5 2019 #27263wordingneutralEP Mazda MX-5 Global Cup classification year changes from 16-18 to 16-19.
FP Clarification of Carb Rules - Prep 1 #27300wordingneutralProduction carb rules clarified: carburetor options, fuel injection throttle body dimensions, and intake manifold restrictions reorganised and refined.
FP Clarification of Carb Rules - Prep 2 #27301wordingneutralEP, FP, HP carburetors clarified: jets, needles, metering rods, needle valves unrestricted; choke parts removable; permitted optional carburetors listed.
T2 Request spare tire/wheel clarification #27012wordingneutralT2-T4 spare tire/wheel rules clarified: removable covers can be removed with hardware and bracketry.
T4 Request spare tire/wheel clarification #27012wordingneutralT2-T4 spare tire/wheel rules clarified: removable covers can be removed with hardware and bracketry.
T4 Research E&O Mazda MX5 #27112suspension & brakesslowerT4 Mazda MX-5 Club (06-15) gains suspension package with 100 lbs weight increase, allows RX8 hubs and SM5 suspension, permits non-OEM LSD with 50 lbs penalty.
FP Request Miata Eligibility - 2003 #27121cars addedneutralEP Mazda MX-5/Miata eligibility years expanded from 1999-2002 to 1999-2005.
SRF3 SRF Dash Windscreen Kit #27028wordingneutralSRF drivers may now use Dash Windscreen Kit P/N 1180103 or P/N 180102.
T2 Request to change Cadillac CTS-V years from 06-07 to 04-07 #26842cars addedneutralT2 Cadillac CTS-V classification expanded from 06-07 to include 04-05 model years.
T2 Request to allow Hotchkiss front / rear sway bars on T2 CTS-V #26845suspension & brakesfasterT2 Cadillac CTS-V 06-07 allowed to use Hotchkiss sway bars up to 36mm front, 25mm rear.
T2 Correct T2 Mustang tire size #27024tyres & wheelsslowerT2 Ford Mustang GT 5.0L tire size reduced from 315 to 295.
T4 MR2 Spyder Year Correction #26936wordingneutralT4 Toyota MR-2 Spyder 16V DOHC years corrected from 01-05 to 00-07.
SRF3 New SRF Sectional Nose Rule Addition #26914wordingneutralSRF3 nose assembly must use approved multi-piece design; no modifications allowed except as specified.
T2 2018+ Audi TT RS Suspension Allowances #26631suspension & brakesfasterT2 2018+ Audi TT RS gains suspension and intercooler allowances: 30mm front sway bar, 28mm rear, 1200lb/in springs, aftermarket intercooler.
T2 Request BOP adjustment for 2018 Honda Civic Type R-TIR removal #26882weight +150 lbsslowerT2 Honda Civic Type-R 2017- weight rises 2900 to 3050 lbs, TIR increases 38mm to 50mm.
T4 Request to allow piggy back ECU on 2000 Mazda Protégé #26085enginefasterT4 Mazda Protégé ES 2000 now allows piggyback ECU tuning device; OBD2 requirement waived.
T4 Request helper spring as optional #26678suspension & brakesslowerT4 Mazda MX5 Club Model 06-15 allows suspension package with 100 lbs weight increase including helper springs.
SRF3 SRF Brakes and Shock Rule Changes #26629wordingneutralSRF3 brakes now allow Hawk Blue 9012 pads P/N 801993 only; shocks simplified to Penske P/N 280396 sealed assembly only, with optional SCCA Enterprises bump rubber P/N 280407 from 05/01/2020.
FP Rollcenter Correction Clarification #25873suspension & brakesfasterEP, FP, HP clarified: tapered holes in ball joints now allowed for bolt conversion; wheel bearings and hubs unrestricted at any wheel.
FP Hardtops #26476wordingneutralEP open cars may now use aftermarket hardtops if they retain OEM appearance; specific model hardtop allowances removed.
T2 Request for Removal of Rear Anti-roll Bar in T2 Mustang GT #26533suspension & brakesfasterT2 Mustang GT anti-roll bars may now be removed or disconnected, previously required as manufactured.
T4 Request to classify 2000 - 2001 BMW 323 #25096cars addedneutralT4 BMW 323 (98-00) newly classified at 3450 lbs with 50mm flat plate restrictor and M52TUB25 engine required.
FP Request Classification of Dodge Daytona in F Production #26259cars added -150 lbsfasterFP Dodge Daytona/Chrysler Laser added at 2100/2153/2205 lbs; Shelby Charger/Omni 024 weight reduced to 2100/2153/2205 lbs.
T2 Request Mustang GT Limited Prep 2018 Classification #24431cars addedneutralT1-LP Ford Mustang GT 5.0L 2018+ classified at 3400 lbs with 65mm flat plate restrictor.
T2 Request to Classify 2018 Audi TT RS #25961cars addedneutralT2 Audi TT RS (2018-) newly classified at 3400 lbs minimum weight with 19-inch wheels and 275 tire size.
T2 Request for Adjustments on 2017+ Civic Type R #25969suspension & brakesneutralT2 2017 Civic Type R allows any sway bar front/rear up to 30mm, front springs to 800lb, rear to 2000lb.
T2 Correct Mazda MX-5 Hard Top Notes #26137wordingneutralT4 Mazda MX-5 Club (06-15) and (2016-), T3 MX-5 Cup and Miata (2016-) hardtop rules clarified; wording changes to permitted parts and specifications.
T2 Consider opening class rules to allow any thermostat #26187wordingneutralT2, T3, T4 now allow any thermostat serving only OE intent, previously restricted.
T2 Ford Mustang Boss 302 (12-13) - correct weight #26287weight -50 lbsfasterT2 Ford Mustang Boss 302 (12-13) weight drops 50 lbs to 3500.
T2 Request camber correction 005-2013 corvette C6 #26288suspension & brakesfasterT2 Corvette C6 Coupe/Grand Sport removes 3.0 degrees MAX front camber restriction.
T2 Request 98-02 Firebird 98-02 Camaro reloacte rear spring #26291suspension & brakesneutralT2 Pontiac Firebird and Chevrolet Camaro SS (98-02) permitted spring relocation to shock.
T2 Cap 2016 Mazda Miata year at 2018 #26388wordingneutralT3 and T4 Mazda MX-5 Miata eligibility capped at 2018 model year, effective 2019-03-01.
T2 Class Ford Mustang GT 2018+ (reference letter 24431) #26400cars addedneutralFord Mustang GT 5.0L 2018+ classified in T2 at 3600 lbs with 50mm restrictor, 19x11 wheels, 315 tyres.
T4 Correct Mazda MX-5 Hard Top Notes #26137wordingneutralT4 Mazda MX-5 Club (06-15) and (2016-), T3 MX-5 Cup and Miata (2016-) hardtop rules clarified; wording changes to permitted parts and specifications.
T4 Consider opening class rules to allow any thermostat #26187wordingneutralT2, T3, T4 now allow any thermostat serving only OE intent, previously restricted.
T4 Cap 2016 Mazda Miata year at 2018 #26388wordingneutralT3 and T4 Mazda MX-5 Miata eligibility capped at 2018 model year, effective 2019-03-01.
T4 2012-2015 Honda Civic Si Performance Request #26129suspension & brakesfasterT4 Honda Civic Si 2012-2015 permitted sway bars increased to 32mm front and rear.
T2 Errors, Omissions, and Updates (Various) #22414wordingneutralT4 Ford Fiesta ST years corrected to 14-; T4 Fiat 124/Abarth Edition years added 16-18; battery rule clarified.
T2 Request to classify 2015 Cayman GTS 3.4L in T2 #25335cars addedneutralT2 Porsche Cayman S/GTS model years expanded from 13-14 to 13-15, now includes GTS variant.
T2 Request for 2017-2018 Honda Civic Type R - 4 BOP Grill #25513wordingneutralT2 Honda Civic Type-R 2017- allows Cuztom Tuning FG-CIV16-V3-TR-BK alternate grill.
T2 Add Clarification to Spec Car Classifications Vehicle Spec #25774wordingneutralT1-T3 spec cars receive clarifications on permitted modifications, documentation requirements, and rule conformance; no performance changes.
T2 Clarify Subframe Bushings Permitted for T2-T4 #25800wordingneutralT2-T4 subframe bushings may now be replaced with non-spherical bushings of any material.
T4 Errors, Omissions, and Updates (Various) #22414wordingneutralT4 Ford Fiesta ST years corrected to 14-; T4 Fiat 124/Abarth Edition years added 16-18; battery rule clarified.
T4 Request for Adjustments to fiat 124 specline #25371inductionfasterT4 Fiat 124 Abarth Edition restrictor changes from 29mm flat plate to 30mm TIR.
T4 Add Clarification to Spec Car Classifications Vehicle Spec #25774wordingneutralT1-T3 spec cars receive clarifications on permitted modifications, documentation requirements, and rule conformance; no performance changes.
T4 Clarify Subframe Bushings Permitted for T2-T4 #25800wordingneutralT2-T4 subframe bushings may now be replaced with non-spherical bushings of any material.
T4 Consider Solo SSC cross over classification into T4 #25802cars addedneutralScion FR-S and Subaru BRZ 13-16 Solo Spec Coupes added to T4, both 1998cc, 2570 lbs, 225/45/17 tires.
Best is the class's fastest lap in that event's qualifying or race sessions, with the driver who set it, how many cars set a time that session and how close the top five were; a best from fewer than three cars is greyed. With two or more classes, "vs" is the gap of each class's best to the first class's at the same event. "% of T4" is the class's best as a share of T4's best at the same event (100% is level, less is quicker): weather and track condition move every class together, so this compares across years where the raw times do not. It still breaks when T4's own field changes or one session was wet and another dry. Newest event first. The coloured figure under each value is the change from the previous event that has one (green is quicker, red slower). Whole laps only, so events with different sector layouts still compare. Weather and track condition are not accounted for.