T1 + SMX + STL + FP at Buttonwillow Raceway Park

Porsche 718 GT4 RS Clubsport: "3450 3325"
Toyota Supra GR GT4: "3350 3225"

Porsche 718 Cayman GT4 CS MR: 3200
Porsche 718 GT4 RS Clubsport: 3450
Toyota Supra GR GT4: 3350

1134: "May resleeve any LS block to LS3 bore/ stroke for Engine replacement. May resleeve to stock parameters for engine repair
or replacement."
1136: "May resleeve any LS block to LS3 bore/ stroke for Engine replacement. May resleeve to stock parameters for engine repair
or replacement."
1138: "May resleeve any LS block to LS3 bore/ stroke for Engine replacement. May resleeve to stock parameters for engine repair
or replacement."
In T1 NEW Spec Lines, Chevrolet Corvette C6 (05-13) - Includes Z51, GrandSport, Z06, Z06 Carbon, change Engine Notes as
follows:
1150: "May resleeve any LS block to LS3 bore/ stroke for Engine replacement. May resleeve to stock parameters for engine repair
or replacement."
1160: "May resleeve any LS block to LS3 bore/ stroke for Engine replacement. May resleeve to stock parameters for engine repair
or replacement."
1170: "May resleeve any LS block to LS3 bore/ stroke for Engine replacement. May resleeve to stock parameters for engine repair
or replacement."
1180: "May resleeve any LS block to LS3 bore/ stroke for Engine replacement. May resleeve to stock parameters for engine repair
or replacement."
1190: "May resleeve any LS block to LS3 bore/ stroke for Engine replacement. May resleeve to stock parameters for engine repair
or replacement."

driveshaft permitted, aftermarket wheels and fuel cell per Touring category rules permitted. Shocks conforming to T1 rules
permitted. Alternative rear toe links permitted."
In T1-GT4 Spec Lines, change Chassis Notes as follows:
Aston Martin Vantage AMR GT4: "**NOT YET ELLIGIBLE FOR RUNOFFS COMPETITION (Q.2)** Slick tires conforming to IMSA GT4
or SRO GT4 specs are permitted."
Audi R8 GT4: "**NOT YET ELLIGIBLE FOR RUNOFFS COMPETITION (Q.2)**Slick tires conforming to IMSA GT4 or SRO GT4 specs
are permitted."
BMW M4 GT4: "**NOT YET ELLIGIBLE FOR RUNOFFS COMPETITION (Q.2)**Slick tires conforming to IMSA GT4 or SRO GT4 specs
are permitted."
Chevrolet Camaro GT4-R: "**NOT YET ELLIGIBLE FOR RUNOFFS COMPETITION (Q.2)**Slick tires conforming to IMSA GT4 or SRO
GT4 specs are permitted."
Ford Mustang GT4: "**NOT YET ELLIGIBLE FOR RUNOFFS COMPETITION (Q.2)**Slick tires conforming to IMSA GT4 or SRO GT4
specs are permitted."
Maclaren 570S GT4: "Slick tires conforming to IMSA GT4 or SRO GT4 specs are permitted."
Mercedes AMG GT4: "Slick tires conforming to IMSA GT4 or SRO GT4 specs are permitted."
Porsche 718 Cayman GT4 CS MR: "Slick tires conforming to IMSA GT4 or SRO GT4 specs are permitted."
Porsche 718 GT4 RS Club-sport: "Slick tires conforming to IMSA GT4 or SRO GT4 specs are permitted."
Toyota Supra GR GT4: "**NOT YET ELLIGIBLE FOR RUNOFFS COMPETITION (Q.2)**Slick tires conforming to IMSA GT4 or SRO GT4
specs are permitted."
In T1-GT4 Spec Lines, change as follows:
Aston Martin Vantage AMR GT4:
Weight: “3575 3490”
Performance Control: “SRO power level ECU Map 3 IMSA Map id 11”
Chevrolet Camaro GT4-R:
Weight: “3375 3435”
Performance Control: “63 62mm”
Ford Mustang GT4:
Weight: “3550 3535”
Performance Control: “63 71mm SRO compliant restrictor IMSA ECU Cal”
Maclaren 570S GT4:
Weight: “3450 3250”
Performance Control: “SRO 2019 BOP ECU map SRO Rest 1”
Mercedes AMG GT4:
Weight: “3450 3470”
Performance Control: “Power level 2 map 5”
Porsche 718 Cayman GT4 CS MR:
Weight: “3200 3250”
Performance Control: “54 53.7mm”
Toyota Supra GR GT4:
Weight: “3350 3315”

Factory Engine Displacement 2000: "Effective 3-1-24: 2700 2625"
In GCR, 9.1.4.H.3., change as follows:
"Front wheel drive cars with a strut type front suspension may reduce their minimum weight by 2.5 percent. Effective 3-
1-24: Front wheel drive cars with 95" or less wheelbase must add 1.25% to their minimum weight."
In STL Spec Lines, change Notes as follows:
Acura/Honda B16: "Effective 3-1-24: 53 51mm"
Acura/Honda B17: "Effective 3-1-24: 53 51mm"
Acura/Honda B18C1: "Effective 3-1-24: 53 51mm"
Acura/Honda B18C (JDM Type R), B18C5 (USDM Type R), B18C6 (UK and Euro Type R), B18C7 (Australia Type R):
"Effective 3-1-24:52 50mm"
Mazda MZR: "Effective 3-1-24: 52 50mm"

In T1 NEW Spec Lines, delete the following Spec Lines in their entirety:
"Acura NSX (Spec Line 1000)
Acura NSX Turbo (Spec Line 1010)
Acura NSX Turbo World Challenge (Spec Line 1020)
Audi TTRS (GTS 2011 Spec) (Spec Line 1040)
Dodge Viper ACR/ACR-X (Spec Line 1360)
Ferrari 360 (Spec Line 1400)
Ferrari 430 (Spec Line 1410)
Ferrari 430 Challenge (Spec Line 1420)
Mazda MX-5 (06-15) (Spec Line 1520 and 1530)
Mazda RX-7 (Spec Line 1540)
Nissan GTR (Spec Line 1550)
Nissan 350/370Z (Spec Line 1560)
Nissan 370Z Supercharged (Spec Line 1570)
Nissan 350Z (Spec Line 1580)
Nissan 350Z/370Z (Spec Line 1590)
Porsche Cayman/S/GTS (05-15) (Spec Line 1600, 1610 and 1620)
Porsche Cayman GTS (2011) (Spec Line 1630)
Porsche 928 S4 Porsche 928 GTS-R (Spec Line 1640)
Porsche 996 (Spec Line 1650)
Porsche 996 TT OEM (Spec Line 1660)
Subaru WRX, WRX STI (05-2020) (Spec Line 1700)
Toyota Celica All-Trac (Spec Line 1710)
Toyota Supra MK4 (Spec Line 1720)"
In T1 NEW Spec Lines, Porsche 997, change Spec Line Number as follows:
"1680 *Spec line Expires 12/23*"

Racing
B. CLASSIFIED CARS
AND WEIGHTS
2006-2015 production-based MX-5
Cars are to be weighed with the driver and required ballast.
C. AUTHORIZED
MODIFICATIONS
Only the left-hand drive, North American-version of the 2006-2015 Mazda MX-5 convertible & power retractable hardtop
(PRHT) are eligible. The original OE vehicle identification number (VIN) stamped on the firewall must correspond with the
model year automobile as classified. VIN plates or stampings must remain in place, with the firewall VIN taking precedence.
A Mazda Factory Shop Manual for the specific make, model, and year of automobile is required to be in the possession
of each entrant. The manual may be in the form of printed material, microfiche, CDs, DVDs, and/ or Internet access to
manufacturer sponsored web-based databases that is readily accessible at time of inspection. The manual is intended to
aid scrutineers in identifying parts and the configuration of the automobile.
The items outlined in this VTS document represent the only modifications and safety items permitted and/or required on
Spec MX-5 vehicles other than safety items as required in SCCA’s current GCR Section
9. Parts and components may not perform an unauthorized function (i.e. Modifications must be stated as authorized or
cannot be done).
If the Mazda Factory Manual or these rules provide only a partial specification or no specification at all, the Mazda parts may
not be modified beyond what is permitted in these rules. Compliance will be determined by comparison to new or like parts
and/or the parts compliance measurement listing delivered by Mazda. Other approved parts with only a partial specification
or no specification available in these rules may not be modified.
Assembly, rebuild, and refurbishment procedures, and all associated dimensions must adhere to the published factory
service procedures, except as otherwise stated in these rules. No components may be added or omitted from those
specified by the published factory service procedures. All components must be comply with stated standard dimensions.
It is permitted to use industry standard procedures to repair damaged components.
The use of any painting, coating, plating, metal treatment process or impregnating substance (e.g., anti- friction, thermal
barrier, oil shedding coatings, chrome, anodizing, REM, isotropic finishing, etc.) to any internal engine surface, internal
axle components, internal transmission or differential surface, internal or external surfaces of the intake manifold, exhaust
manifold or down tube, is prohibited.
D. VEHICLE
TECHNICAL
SPECIFICATIONS
(VTS)
1. Vehicle Weight
a. The minimum vehicle weight with driver is 2,525.0 lb.
2. Ballast
If ballast is required to meet the required minimum weight, it must be added as follows:
a. A ballast base plate must be securely mounted using the factory OE passenger seat mounting bolt holes and bolts. Any number
of additional segments of ballast may be attached to the base plate.
b. Each segment of ballast must be fastened to the base plate with a minimum of two (2) one-half (1/2) inch bolts/studs and
positive lock nuts of SAE Grade 5/ Metric 8.8 or better and must utilize large diameter, load distributing washers. In lieu of
positive lock nuts it is permitted to positively thread the additional segments of weight into the base plate.
c. Holes are not permitted to be drilled in the floor pan to mount ballast.
3. Chassis
a. Towing eyes per SCCA’s current GCR Section 9.3 are required. There must be an arrow that strongly contrasts with the vehicle
paint scheme pointing to each tow eyestrap.
9.1.7.1 SPEC MX-5 (SMX)
b. All cars must use the front subframe PT# - NE51-34-800C
c. All cars must use the rear subframe PT# - NE51-28-800B.
d. OE strut tower brace is required; it is comprised of three (3) components; see Table 1 for part numbers.
e. An engine to fender brace located on the passenger side of the engine bay may be used if mounted in such a way that it does not foul brake
lines, fuel lines, or other systems that would interfere with the safe operation of the vehicle under race conditions – see Table 1 for allowed
modifications. (Mazda Motorsports PT# 0000-07-5600)
f. Disabling or removing of the door locking mechanism must be performed.
g. To facilitate frequent lifting of the vehicle, a 3/4” boxed tube not to exceed 12” long may be added under the rocker panel inboard of
the factory pinch weld flange on each side of the vehicle.
h. Convertible tops/power retractable hard tops (PRHT) and attaching hardware must be completely removed.
i. All chassis, structural, and electrical repairs, if performed, must be in conformity with factory procedures, specifications, and dimensions.
Unless specifically authorized by the manufacturer for repair or permitted by these rules, no reinforcement (e.g., seam welding, material
addition, etc.) is permitted.
j. Removal of excess wiring is permitted provided it serves no other purpose and does not splice or interrupt the OE harnesses. Removal of the
following systems is permitted: audio equip- ment; power seats; airbag/supplemental restraint systems components; heated seats; interior
lighting; power windows; and power door locks. (No additional wiring may be added except as permitted in other sections - e.g., Section 16:
Electrical Equipment.)
Table 1: Strut Tower Brace Parts
Description Mazda Part #
Right Side of Strut Tower
Brace
NE57-56-48X
Left Side of Strut Tower
Brace
NE57-56-49X
Center Section of Strut
Tower Brace
NE57-56-48ZA
k. A hole is permitted to be drilled in part #’s NE57-56-48X and NE57-56-49X to allow for access to the shock adjuster screw is permitted (it is
recommended that the hole not be larger than 15mm); NE57-56-48X may be modified in order to allow room for the engine passenger side
engine brace; no other modifications or other braces are permitted.
l. MX-5 donor chassis with originally equipped with 16” OE wheels require installation of
OE strut tower brace (part # NE57-56-35XA).
m. To facilitate engine bay air flow for cooling purposes it is permitted to remove the section outlined below in red from OE PT# NE57-56-
35XA. Block-off plates must be installed at the fresh air vent for the HVAC module at the firewall under the cowl to isolate driver
compart- ment from engine compartment.
(FIREWALL BLOCKOFF PLATE 0000-07-5832) No additional modifications are permitted.
4. Body
a. Interior and exterior door handles are required to remain operable. Alternate interior door handles or cord/strap are permitted.
b. The driver’s and passenger’s side inner door structural panel may be removed to fit the cage.
c. The stock side impact/anti-intrusion beam must not be modified or removed.
d. Door locking mechanisms must be disabled or removed.
e. A minimum of two (2) of the brake lights must be in working order per the current GCR Section 9.1.
f. The two (2) OE unmodified, external mirrors for the correct the Mazda MX-5 (left and right) are required; they must be
mounted in stock location and may not be modified.
g. OE interior rearview mirror or an aftermarket rearview mirror must be used.
h. 2006-2015 MX-5 bodywork may be updated or backdated, OE body parts only. (This includes Mazda OE accessory body
parts such as trunk lid spoiler, side skirts, front air dam.)
i. Mazda Motorsports’ fiberglass headlamp replacements may be used; (See table 2)
no modifications or substitutions are permitted; exceptions: painting, covering, and wrapping.
Table 2: Headlamp Replacement Covers
Model Year Mazda Part # Description
2006-2008 0000-07-5818-LT Left Side
2006-2008 0000-07-5818-RT Right Side
2009-2015 0000-07-5819-LT Left Side
2009-2015 0000-07-5819-RT Right Side
j. Lexan windshield may be used in place of the stock windshield. (Mazda Motorsports PT# -
0000-07-5101-5S)
k. Windshield clips per current GCR Section 9.3 windshield clips are recommended.
l. Hood and trunk pins or clips are permitted. Factory hood and trunk latches must remain intact and operational and may not be
removed, disabled or altered.
m. Front under hood weather strip must remain intact PT#- NE51-56-750
n. Rear under hood weather strip must remain intact PT#- NE51-56-760
o. Modification of release cables is permitted to facilitate external pull/opening straps/pulls/cords.
p. A radiator screen of 0.125” minimum stainless-steel mesh may be added in front of the radiator.
1. The screen must be a single layer and must be installed to the bumper cover and or grill and be contained entirely within the
bodywork of the vehicle.
2. Tape may be applied to the mesh screen.
3. The OE grill must remain intact.
q. It is allowed to apply roll bar padding to the crash support bar (52-070) located behind the front bumper to prevent damage to the
bumper.
r. Front and rear fender lips may be rolled to prevent tire damage.
s. Front OE fender liners must be intact and unmodified, except for what is allowed in section 13. J regarding brake ducts.
Repairs due to on-track damage is allowed so long as it serves no other purpose.
t. OE fog lights lens/glass must be removed. This will allow for the installation of brake duct kit (Mazda Motorsports’ part # 0000-03-
5301-NC.) The remaining opening from the fog light lens must either be blocked, or a connection must be made from the fog lamp
opening/hole in the bumper fascia to a brake duct attached to the hub.
u. Side marker lenses may be removed, and holes may be covered.
v. OE hard top or the unmodified Mazda Motorsports hard top (part # 0000-07-5901-CC)
are permitted.
w. PRHT chassis cars must trim the finish panel with the 3rd brake light to fit one of the approved hard tops.
1. Hhardtops may be painted or wrapped.
2. OE hard top latches must be removed and replaced with positive fasteners.
3. The front of the hard top may attach to the upper windshield bar of the roll cage.
4. It is permitted to run one single piece of racer tape to cover the leading edge of the after- market hard top where it meets
the factory windshield frame.
5. Openings beneath the hard top seal to the body are not permitted. The hard top must be securely mounted to the body of the vehicle
and perform no other purpose.
6. Body repair must be performed to maintain stock body contours, lips, profiles, etc. body repair modification must not increase clearance.
x. To improve driver’s exit through the window area, the driver and passenger vent window and vent window supporting frame may be removed
as an assembly.
1. Vent windows may be modified to accept fresh air ducting.
y. OE radio antennas may be removed. Antennas for two-way radios may be added.
z. Insulation & undercoating may be removed.
aa. All cars must run with both the front door windows fully open (i.e. fully down).
5. Cockpit /
Trunk
a. All interior trim components such as carpets, seats, cargo bins, seat belts, floor mat, firewall insu- lation/blanket, sound deadener patches,
undercoating, radio systems, speakers, dome lights, grab handles, sun visors and their insulating and attaching materials, must be removed.
Other than to provide for the installation of required safety equipment or other authorized modifications, no other driver/passenger
compartment alterations or gutting are permitted.
b. It is permitted to install a radio replacement panel.
c. The outer edges of the dashboard may be cut the minimum amount required to install the roll cage.
d. Air bag systems must be disarmed and must be removed.
e. It is permitted to remove all components of the cruise control system.
f. The top portion of the door panels containing the door latch release handle must remain intact.
g. The lower portion of the door panels must be removed for installation of the roll cage. Gutting of the door may not go outside of the factory
seal.
h. The door window glass and window operating mechanisms must be removed.
i. The OE dashboard and its attaching hardware and brackets must be retained.
j. For installation of required safety equipment, however, it is permitted to modify the OE dash bar, so long as it is outboard of the first dash support
brackets (illustration below). Modification of the first dash support brackets, nor inboard from them, is not permitted. The OE dash bar must be
securely mounted.
k. The HVAC control module located under the dash may be removed together with the following: blower motor, evaporator core,
heater core and associated ducting. Once removed it is permitted to block the blower inlet passage on the firewall.
l. All openings between the driver/passenger compartment and the trunk / gas tank area that include the filler tube & fuel tank vent
must be filled completely with a metal bulkhead that is securely mounted (E.G. nuts/bolts, nut-serts, rivets). This shall close the
entire trunk from the driver/ passenger compartment and comply with current GCR Section 9.3.
m. Mazda Motorsports’ finish panel trim kit (part # 0000-07-5822) may be used to create the required bulkhead above
n. It is permitted to remove the driver’s side factory seat mounts, but not the floor pan.
o. It is permitted to remove the horn and all associated horn related components.
p. OE driver’s seat must be replaced with a one-piece bucket-type race seat per current GCR Section 9.3.
q. The passenger seat must be removed.
r. Any steering wheel except wood rimmed types may be used.
s. Any shift knob may be used.
t. The air conditioning equipment located in the engine compartment (AC compressor assembly, associated lines/dryer and the
condenser) must be removed.
u. Alternate gauges and instruments may be added. The original instrument cluster must remain connected and functional However,
it may be relocated to allow the mounting of an aftermarket dash such as an AiM. The wiring to relocate the dash may not be cut or
extended, it may only be re-routed. The remainder of the dashboard or panel must remain intact.
v. Modifications may be made to the foot pedals to improve the comfort and accessibility to the driver; relocation of mounting
points is not permitted.
1. Dead pedal/footrest and heel stop may be added.
w. Instrument clusters must be unmodified OE parts .
x. Two-way radios may be used.
y. Alternate means of windshield defrosting is permitted
6. Engine
Modifications
6.1. General
a. No modifications to the engine are permitted, except where specifically authorized within these rules. This includes but is not
limited to: all fuel injection and engine management components, as well as electrical, cooling, and lubrication systems.
b. All systems, unless otherwise stated, are subject to test procedures and must conform to OE
specifications as stated in the Mazda Factory Service Manual.
c. Permitted engine maintenance includes the replacement, but not modification, of external engine and engine systems parts.
1. No balancing, blue printing, lightening, polishing or other modification of moving parts of the engine is permitted.
2. All parts in the engine must be OE parts unless specified in this rule set.
3. For all Mazda part numbers in these specifications, superseding part numbers are consid- ered equivalent.
d. Compression ratio for 2.0L engines must be 11.00:1; calculated using the official Spec MX-5 calculator.
6.2. Engine Block
a. The engine block may be decked or milled to achieve the class specified compression ratio. Honing of cylinders is permitted to accommodate
piston clearance so long as a maximum standard diameter is not exceeded shown in Table 3.
b. The cylinders may be bored to accommodate piston clearance requirements so long as maximum permitted overbore diameter is not exceeded
shown in Table 3 below.
Table 3: Piston Sizes
Piston Part # Bore Diameter Max
Standard 0000-01-5310 87.6046mm (3.449”)
Allowed Overbore (.020) 0000-01-5310-OS 88.1126mm (3.469”)
c. It is not permitted to overbore a single cylinder; all cylinders must be bored equally.
d. Sleeving of cylinders is not permitted.
6.3. Crankshaft
a. OE Mazda MZR 2.0L (2009-2015) manual transmission crankshaft (part # LF9G-11-301) must be used with no modifications except for
machining or polishing polishing and/or machining of the bearing surfaces to allow the use of main and rod bearings as permitted
in Table 4 below.
Table 4: Crankshaft Measurements
easurement iameter Diameter
b. OE crankshaft (Mazda part # LF9G-11-301) must weigh a minimum of 31.75lb.
c. Maximum permitted stroke is as follows: 3.27” / 83.1mm
d. Shot peening is prohibited.
e. Bearings
1. Main and rod bearings must not be modified; coatings are not permitted.
2. OE bearings are permitted.
3. The only bearing sizes permitted other than OE are listed in see Table 5.
Sizes
Bearing Type Minimum Bearing
Width Minimum Bearing
Thickness Minimum Bearing
Weight Part #
Main Bearings
(Standard H) .630” 0.097” N/A 0000-01-5215-MB
Main Bearing
(Standard HX) .630” 0.097” N/A 0000-01-5216-MB
Rod Bearings
(Standard H) .630” 0.057” 28g 0000-01-5213-RB
Rod Bearing
(Standard HX) .630” 0.057” 28g 0000-01-5214-RB
f. The crank trigger must not be modified; it must be installed per the Mazda Factory Service Manual.
g. OE crank pulley/balancer (Mazda part # LF94-11-400) must not be modified and must be installed per the Mazda Factory Service Manual.
h. Knife edging of the crankshaft is not permitted.
i. Modifications to the crankshaft counterweights are not permitted.
j. Coatings, REM or metal treatments of any kind are not permitted.
k. Alternate shifter bushing located at the bottom of the shift lever is allowed.
6.4. Connecting Rods
a. OE Mazda MX-5 (2009-2015) manual transmission unmodified connecting rods (part # LF9G- 11-210) must be used. Connecting
rod weight with cap and bolts must not be less than 530 grams.
6.5. Pistons
a. Mazda Motorsports’ competition pistons (standard bore part # 0000-01-5310; oversized part # 0000-01-5310 OS) are required;
no modification is permitted.
b. The minimum weight of the piston, less wrist pin and hardware, must not be lighter than 290 grams.
c. Mazda Motorsports’ competition wrist pin (part # 0000-01-5310-PN) must be used.
d. The minimum weight of the wrist pin must not be lighter than 80 grams.
e. Modification of the piston ring end gap width is permitted.
6.6. Cylinder Head
a. Mazda Motorsports’ competition cylinder head (part # 0000-01-5300) must be used; no modi- fications to the cylinder head are
permitted outside of the gasket face surface outlined below in Table 6.
b. Intake runner CC volume is 182cc +/- 1cc.
c. Exhaust runner CC volume is 114cc +/- 1cc.
d. Combustion chamber volume may not be below 41cc.
e. The gasket face of the cylinder head may be resurfaced provided the maximum allowed compression ratio is not
exceeded.
I. Surfacing of the head gasket surfaced must be in a flat plane.
II. Cylinder head gasket surface distortion may not exceed .010mm or 0.004”.
f. The minimum height of the cylinder head as measured must be at least (TBA)
g. The following head gaskets in Table 6 below are permitted; no other gaskets may be used.
Table 6: Head Gasket Measurements
Description Thickness Mazda Part #
OE Gasket 0.017” approximate crush
depth L3G2-10-271A
Competition
Gasket 0.55mm (0.021”) 0000-01-5319-21
Competition
Gasket 0.75mm (0.030”) 0000-01-5319-30
Competition
Gasket 1.0mm (0.040”) 0000-01-5319-40
Competition
Gasket 1.3mm (0.051”) 0000-01-5319-51
6.7. Camshaft and Camshaft Timing
a. Camshafts must not be modified; see Table 7 for OE camshaft part numbers.
Table 7: Camshaft part numbers
Description Mazda Part #
Intake Cam L3E3-12-420
Exhaust Cam L309-12-441B
b. Camshaft and crankshaft sprockets must not be modified; see Table 8 for part numbers.
shaft Sprocket Part #s
t #
4X0C
425
c. Cam timing must not be altered; chain must be installed as stated in the Mazda Factory Service Manual.
d. OE timing chain (Mazda part # LF7A-12-201) is required; no modification is permitted.
e. OE timing chain components must be used; see Table 9 for Mazda part numbers.
Table 9: Timing Chain Guide Part #s
Description Mazda Part #
Fixed Guide LF01-12-614
Tensioner Guide LF01-12-671
6.8. Valves
a. OE valves must not be modified (including reshaping); see Table 10 for Mazda part numbers.
le 10: Valve Part #s
b. Valve location or angle must not be moved.
c. Valve guides may not be replaced.
d. Valve job measurements must be as follows:
1. Intake 35 top 45 seat 65 bottom 77 bottom seating angle width is 1.0mm
2. Exhaust 40 top 45 seating to radius seating angle width 1.2 mm.
3. Valve stem installed height must be per the Mazda Factory Service Manual.
4. Valve stem seals must be OE.
6.9. Valve Springs
a. Mazda Motorsports’ competition valve springs (part # 0000-01-5319-SP) are required.
6.10. Intake Manifold
a. OE intake manifold (Mazda part # LF9G-13-130B) is required; no modification is permitted (e.g., no material may be added or removed; no
painting or coating on the exterior or interior permitted).
b. All air entering the engine must pass through the throttle body and metered by the mass airflow sensor.
c. Removal of these factory EGR components is permitted: Valve, crossover pipe, coolant lines (EGR DELETE KIT 0000-06-5447)
d. If factory EGR components are removed, the following ports must be blocked:
1. Intake manifold cross over pipe port.
2. Cylinder head cross over pipe port.
3. EGR valve port on back of cylinder head.
6.11. Intake System
a. Cars must replace OE air box with the Mazda competition cold air intake kit (part # 0000-06- 5150-KT); no modification (e.g., ducting or
baffling of air, venturi cones) to the cold air intake kit is permitted.
b. No alteration to the intake tube length, diameter, or shape is permitted.
c. The air filter supplied in the Mazda Motorsports competition cold air intake kit may be refreshed
with the Mazda Motorsports’ competition air filter (part # 0000-06-5204).
6.12. Fuel System
a. Fuel must comply with SCCA GCR section 9.3.25
b. OE fuel pump (Mazda part # LFG1-13-350) is required; no modification is permitted.
c. It is permitted to remove the unleaded fuel restrictor from the filler neck. (GCR 9.3.26)
d. Mazda Motorsports’ competition fuel rail that includes fuel pressure gauge, and fuel sampling test port and hose kit (part #
0000-06-5207) is optional.
1. Fuel pressure sensor integrated into the required AIM data acquisition system is required. It must be operational and able to be
viewed when pulling a competitor on track data.
2. The addition of a switch or jumper located in the under-hood fuse box is allowed to acti- vate the fuel pump. This modification may
serve no other purpose.
3. One operational fuel sample test port is required. Fuel sample test ports shall be made from dry break fuel rated quick disconnects.
No other style of fuel sample test port is allowed (e.g., Schrader valves).
4. No other modifications permitted.
e. OE fuel pressure regulator (Mazda part # LFB6-13-280) is required.
1. Vehicle must run between 54 and 63 PSI of fuel pressure.
f. OE injectors (Mazda part # L3G5-13-250) are required; no modification is permitted.
1. Flow rates for the injectors must fall within the factory tolerance of 204-216ml (204-216 cc, 12.5-13.1 cu in/minute).
6.13. Lubrication System
a. OE engine oil filter is required; no substitutions permitted.
b. OE oil pump PT# L310-14-100J is required and no modifications are permitted.
c. Mazda Motorsports’ competition oil cooler adaptor kit with lines (part # 0000-01-5100KT) is required; no modification is
permitted.
d. Oil pressure sensor integrated into the required AIM data acquisition system is required. It must be operational and able to be
viewed when pulling a competitor on track data.
e. Oil and lubricants are unrestricted.
6.14. Engine Control Unit (ECU)
a. Reference penalties for non-compliance of the Spec ECU flash in Section 21 below. Modifica- tion or attempted modification of
the Spec ECU flash will result in a 12-month suspension from competition and $1,000.00 fine.
b. Mazda Motorsports’ competition ECU (part # 0000-01-5379) is required; serial number must be visible; external or internal
modification is not permitted.
c. ECU calibrations and inputs must not be modified.
d. OE engine electrical harness (part # NH18-67-020A) is required; no modification is permitted.
e. OBDII diagnostics port must be operational in all cars.
1. The check engine light must be operational and perform the function test at start up.
2. The OBDII port must be available at all times (including during the race) for tech officials to install test equipment as necessary.
3. If a competitor uses the OBDII port to power any type of data acquisition system, he/she would be responsible for providing the
splitter cable to plug in both units or unplug the data acquisition system.
f. Instrument panel clusters must be operational and unmodified OE parts.
g. Temporary data acquisition devices may be installed by the sanctioning body for technical compliance.
h. Removal of Mazda ECU insulator PT# LFG1-13-3C1 is permitted (diagram below)
6.15. Miscellaneous
a. The factory air conditioning system and all associated lines, compressor, condenser and evap- orator must be removed.
1. Once the AC compressor is removed, the OE AC pulley delete kit (Mazda part # LF17-15- 940E) is required.
b. Serpentine belt Gates PT# 6PK-2170 or same size equivalent is required.
7. Exhaust
a. OE exhaust manifold and OE heat shield must be replaced with Mazda Motorsports’ competi- tion part # 0000-06-5407-NC; no modification
is permitted (e.g., internal or external wraps, coatings, paints, metal treatments, thermal barriers etc.).
b. OE exhaust system must be replaced with Mazda Motorsports’ competition part # 0000-06- 5427-NC; no modification is permitted (e.g.,
internal or external wraps, coatings, paints, metal surface treatment, thermal barriers etc.).
c. The forward oxygen (O2) sensor (OE Lambda Sensor) must remain in the factory location and in full working order. Mazda Motorsports’
competition O2 sensor installation kit wiring extender (part # 0000-10-5320) is permitted.
d. The secondary post catalytic oxygen (O2) sensor must be removed.
e. Heat shielding
1. OE heat shield protecting ABS unit from header may not be removed or modified.
2. OE muffler heat shield may not be removed or modified.
3. It is permitted to wrap the exhaust pipe from the mid connection flange to the muffler.
(see red arrows in picture below)
4. Use of heat shielding material on transmission tunnel to replace OE heat shielding is permitted. OE heat shielding
must be removed from transmission tunnel. (see diagram below)
8. Cooling System
(cooling system
checklist)
a. Mazda Motorsports’ competition radiator and oil cooler assembly (part # 0000-01-5504-CR) is required (e.g., OE is not
permitted).
b. The radiator using the OE mounting brackets must be installed in its original location.
c. The oil cooler may not be moved or altered from the pre-assembled mounting location.
d. Radiator ducting may be placed on each side of the radiator tanks and the undertray to force air through the radiator fins. The
gap between the top and sides of the radiator may be sealed but shall not perform any other function.
e. The unmodified OE cooling fan must be maintained in full working order and mounted in the stock location. Axillary control of
the radiator cooling fan may be added to activate the fan independent of the ECU, OE control of the fan must remain intact.
f. Thermostats may be modified, removed or replaced.
g. The OE water pump (Mazda part # 1F70-15-100) is required; no modification is permitted.
h. The OE water pump pulley (Mazda part # L327-15-131) is required; no modification is permitted.
i. Engine cooling system hoses and clamps may be substituted.
j. The heater core may be removed along with HVAC evaporator core including all associated hard pipes and hoses. This is to include
OE water to oil cooler lines as well as throttle body coolant lines. (Rear coolant pipe 0000-01-5514, bottom coolant pipe 0000-
01-5515)
k. The OE engine coolant expansion tank may be replaced with any aftermarket part but and must not serve another purpose.
9. Clutch, Pressure Plate and Flywheel
a. Vehicle may use any combination of the options listed in Table 11 below.
Table 11: Clutch Component Part Numbers
Description Mazda Part #
Mazda Factory Clutch Disc LF05-16-460A
ACT Sprung Clutch Disc 0000-02-5420-AC
ACT Pressure Plate 0000-02-5405-AC
ACT Clutch and PP Kit 0000-02-5004-G6
Mazda Factory
Pressure Plate LF04-16-410A
b. The unmodified pressure plate must be bolted directly to the stock, unmodified flywheel.
c. OE flywheel (Mazda part # LF9G-11-500) is required. Factory Service Manual resurfacing specification is permitted; no
other modification is permitted.
d. Alternate clutch lines are permitted but must not serve another purpose.
e. Clutch components must adhere to the minimum weights listed in Table 12 below:
Table 12: Clutch Component Part Numbers
Description Minimum Weight (lb.)
Clutch disc 3.5
Pressure Plate 9.4
Flywheel 15.80
10. Transmission
a. OE 2006-2015 6-speed gearbox and 4.10 final drive ratio are required.
b. No modification of the internal parts and ratios are permitted except the installation of the unmodified parts contained in the Mazda
Motorsports MX-5 transmission upgrade kit (part # 0000-02-5700).
c. Mazda Motorsports Competition gear set 0000-02-6000 is allowed. Gear ratios are as follows: 1st - 3.82; 2nd - 2.26; 3rd - 1.64;
4th - 1.18; 5th - 1.00; 6th - 0.83/0.79. There are two (2) production 6th gears; either one is permitted.
d. Alternate shift knobs are permitted.
e. Nomex or aftermarket fireproof shift boots are permitted. Removal of the factory rubber shift boot is not permitted.
f. No treating, coating, polishing or modification of any transmission or components are permitted.
g. Fluids and/or lubricants may be substituted with any lubricant.
h. Updating or backdating of transmissions from 2006–2015 is permitted; unmodified OE shifters must be retained. The use of short throw
shifters is prohibited.
i. An single inspection hole (not to exceed 1.5” in diameter) in the bottom of the bell housing is permitted for the sole purpose of technical
inspection of the flywheel. It is permitted to plug or tape over theat hole.
j. Transmission cooler(s) are permitted.
11. Differential
a. Only the Following differentials are allowed.
1. Mazda Motorsports, unmodified, Torsen limited slip differential – 0000-02-5564
2. OE, unmodified, limited slip differential - Mazda part # MS03-27-200B
3. OE, unmodified, open differential are permitted.
b. RX-8 differential mounting bracket (Mazda part # F151-39-730B) is permitted.
c. Mazda Comp diff bushings 0000-04-5510 is permitted (MX-5 diff mount)
d. Polishing, metal treatment or coating of differential or axle components are not
permitted.
e. Removal of metal/rubber isolator on the pinion flange is permitted.
f. Differential cooler(s) are permitted.
12. Suspension and Steering: Suspension
Modifications are limited to the addition of the Mazda Motorsports Spec MX-5 kit; details are as follows (including all
modifications permitted):
a. OE control arms are required; no modification is permitted.
b. Mazda Motorsports’ TSB MX-5-002 must be followed re: the rear shock thread protector found in the “Spec MX-5: Four Pillars”
page on MazdaMotorsports.com. The thread protector must measure 1.250”. (The TSB will not be applicable to the supply from
Mazda Motorsports received after 7.15.2020 as they will have the updated thread protector.)
c. Anti-roll bar links may be replaced with Mazda part # 0000-04-5597-KT
1. Cockpit adjustability is not permitted.
d. Mazda Motorsports’ competition sway bars are required, mounting guidelines:
1. Metal shims up to 1/8” total thickness are permitted between each anti-roll bar mount shackle and the stock mounting
point on the chassis.
2. One end of the sway bar(s) may be disconnected as a suspension tuning aid.
3. The bar must remain in place and be solidly attached to the suspension on one end.
4. Sway bar end links must be installed on the unmodified stock attachment points.
e. Camber, caster, and toe are unrestricted within the limits of the unmodified factory adjust- ments in conjunction with Mazda
Motorsports front offset bushing (part # 000-04-5407-NC).
f. Minimum ride height is unrestricted.
g. Nuts & bolts may be replaced by similar items performing the same fastening function(s).
h. Relocation or reinforcement of any suspension parts or mounting points is not permitted, with the following exceptions:
1. Addition of spacers or washers on a horizontal plane is permitted at the rear lower shock mount to the spindle per the
shock installation instructions.
2. Updating to RX-8 rear toe link and rear trailing arm is permitted. See Table 13 below.
Table 13: Permitted RX-8 Trailing Arm and Toe Link Part #s
Description Mazda Part #
RX-8 Trailing Arm F189-28-200A
RX-8 Toe Link F189-28-45XA
i. OE power steering pump with pulley (Mazda part # NE51-32-650D) is required; Mazda Motor- sports Power steering flow
restrictor PT#- 0000-04-5532 is permitted; no other modification is permitted.
j. OE power steering rack (Mazda part #: NE51-32-110C) is required; no modification or reloca- tion is permitted.
k. Factory power steering reservoir may be replaced.
l. Wheel center caps must be removed.
m. All chassis, structural and electrical repairs must follow factory procedures, specifications, and dimensions as described in the
applicable service manual. Reinforcement (e.g., seam welding, material addition, etc.) is not permitted.
n. Steering lock mechanisms must be removed.
o. The distance from the outside of the wheel rim to outside of the opposing wheel rim for both the front and rear of the vehicle
must not exceed 69.5”.
I. The distance Measurement is obtained by measuring the distance between the wheel lips by going through
the wheel spokes at the bottom of the wheel at its widest point via tape measure. (Measure the outside wheel
lip of one wheel to outside wheel lip of the other wheel on same axle.)
p. Mazda Motorsports’ competition rear toe link (part # 0000-04-5426) is permitted; no modification is permitted.
q. Mazda Motorsport’s Spec MX-5 Suspension Kit includes the items set forth in Items in Table
14. seen below are components within this kit. No substitutions or modifications of parts are permitted. The
unmodified kits must be used in their entirety, except as specified.
Table 14: Spec MX-5 Suspension Kit (All parts are required; no modification is permitted.)
Description Location Mazda Part #
Shocks Front 0000-04-5291-SA
Rear 0000-04-5292-SA
Springs Front 0000-04-9700-08
Rear 0000-04-9400-07
Helper Springs Front/Rear 0000-04-9926
Front Penske
Mount Kit Front 0000-04-5359
Rear Penske
Mount Kit Rear 0000-04-5358
Sway Bar Kit Front and Rear 0000-04-5306-EB
Offset Bushings Front 0000-04-5407-NC
13. Hubs
a. OE RX-8 front hub (Mazda part # F189-33-04X) may be substituted in place of the OE Miata 2006-2015 front hub.
b. Mazda Motorsports’ competition RX-8 rear hub upgrade kit (part # 0000-04-5811-KT) may be substituted in place of the OE MX-
5 rear hubs; this unmodified kit must be used in its entirety.
c. OE RX-8 rear uprights, bearings, hubs, and hybrid axel may be used in place of OE MX-5 parts.
14. Brakes
a. OE brake rotors must be used and adhere to the specifications below in Table 15.
Table 15: Brake Rotor Dimensions
Location Diameter Notes
Front 290mm (11.4”) Vented
Rear 280mm (11.0”) Solid
Front backing plates/dirt shields may be removed.
(see see red arrow in diagram below)
b. Rear backing plates/dirt shields may be removed.
(see red arrow in diagram below)
c. Brake lines may be replaced with competition braided steel lines; option: Mazda Motorsports’ part # 0000-03-5212.
d. The Factory ABS system must remain intact, unmodified, and in full working order.
e. Brake slider pin may be used in either/both front location B25D-33-694. (This prevents a stuck sliding caliper due to the rubber
grommet)
f. Parking brake mechanisms and actuating components may be removed.
g. Brake fluid is unrestricted.
h. Mazda Motorsports’ competition brake duct kit (part # 0000-03-5301) is permitted.
i. The forward vertical inner fender panels may be modified to fit the brake kit hose to the fog light openings but may not be
modified to serve any additional purpose.
j. Mazda Motorsports’ competition brake pads are required; see eligible brake pad compounds in Table 16. No other brake pads
are permitted.
Table 16: Brake Pad part numbers
Pad Style Mazda Part # Notes
Front Pad 0000-03-5104-SP RST-3 compound
Rear Pad 0000-03-5116-29 RSL-29 compound
15. Wheels
The following unmodified wheel options below in Table 17 are permitted for use.
Table 17: WHEELS
Description Color Mazda Part #
17x7” OE Wheel Gun Metallic 99656-47070
17x7” OE Wheel Silver 99656-77070
Mazda Motorsports’ Competition MX-5 Wheel Gun Metallic 0000-04-5706-GM
Mazda Motorsports’ Competition MX-5 Wheel Silver 0000-04-5706-SL
a. Wheels may be painted.
b. Aftermarket (any) wheel studs and lug nuts are permitted., provided that a minimum of two he threads must protrude
beyond the lug nut with the wheel installed with a minimum of two (2) full threads showing; Wheel studs may not be gun
drilled.
c. Wheel spacers are not permitted.
16. Tires
a. Dry tires: Toyo RR P235/40/ZR17
b. Wet tires: Toyo RA1 P235/40/ZR17.
17. Electrical Equipment
a. OE ignition coils (Mazda part # L3G2-18-100B) are required; no modification is permitted.
b. Mazda’s competition spark plugs (part # 0000-10-R7IX-11) are required; no modification is permitted.
c. The crankshaft position sensor and crankshaft pulley relationship must be as specified in the 2006- 2015 MX-5 Factory Service Manual.
d. One of the two OE alternators (Mazda part # LF9H-18-300R-OA, L3P9-18-300D) is required; no modification is permitted.
e. The alternator must not be externally regulated or disabled in any way other than by the OE
production ECU/wiring circuit and master kill switch.
f. The electronic control module (ECM) control circuit for alternator charging must be OE - unmodified and operational.
g. One of the two OE alternator drive pulley part # AJ51-18-W10 (60mm), Part# L813-18- W11(55mm) is required; no modification
is permitted.
h. All sensors related to engine operating parameters must be used and must be stock, unmodi- fied Mazda parts for the correct year
of the vehicle on which they are installed.
i. Any and all sensors and their respective locations, mounts, and wiring harness leads may not be altered except as elsewhere in this
rule set. e Spec-MX-5 rules.
j. Any sensors required for non-OE gauges must be in addition to the Mazda sensors.
k. All alternate gauge and sensors must have independent wiring. Splicing, tapping, or altering
of the factory engine wiring harnesses is prohibited with the exception of adding an
aftermarket tachom- eter/shift light as follows:
1. It is permitted to splice into the yellow wire with the black stripe (pin 2BA - Ignition
Coil 1 control circuit) in the engine harness to obtain the tachometer signal for an
aftermarket tachometer or shift light.
2. Splicing must be done within 5” of the ECU.
l. Data acquisition’s sensor(s) may be added, provided they do not require splicing or
alteration to the factory engine wiring harness.
m. Batteries
1. Batteries may be replaced with those of an alternate manufacturer, provided they are of
similar amp-hour capacity, and size, including lead acid or AGM.; lLithium batteries are not
permitted.
2. Batteries must weigh no less than 18.0lb and no more than 35.0lb
3. Additional battery hold-down devices are recommended.
4. Battery MUST be moved from the original location to the passenger side
in the upper trunk area in front of the tail lamp. This will require the use
of a bulkhead that separates the driver / passenger compartment
completely from the trunk and the battery location. See section 5.I for
reference.
18. Roll Cage
a. Roll cage must adhere to SCCA’s current GCR Section 9.4 for Touring 4 cars; with the following exceptions:
1. One tube not to exceed 1.75” in diameter may be added which extends from the door bars to the rocker panel on each side.
The landing plate for this tube can be no longer than 5” in length. The landing plates must be centered between the front
and rear landing plates for the lower NASCAR or X brace bar.
2. Main hoop mounting plates may be on multiple planes; however, they must not be greater than 19” on any side.
b. Playboy MX-5 Cup car cages manufactured by Racing Cages, Inc. with the official serial number plate on the main hoop are
allowed to retain the lower door bar and two 3” attachment points to the rocker panel on both the driver’s side and passenger
side. No additional seam welding or lengthening of the original attachment points is allowed.
19. Safety
a. An electrical master (“kill”) switch is required. See current GCR Section 9.3 Master Switch.
b. Vehicle must be equipped with a driver’s restraint system meeting the specifications of current GCR Section 9.3 Drivers
Restraint System.
c. Installation of a fire extinguisher or fire system is required. See current GCR 9.3 Fire System.
d. Vehicle must have a driver’s side window safety net complying with current GCR Section 9.3 Window Safety Nets. Nets must be
mounted to provide protection in the event the driver’s door opens.
20. Data
Acquisition
1 A technical evaluation process for cars is available from the Series. Part of this process is the required download of AiM Data files after
each timed session (Qualifying 1 & 2, Races 1 & 2). Within 30 minutes of each timed session end, all Series Competitors MUST send
the AiM Data file (.XRK) for all timed laps of that session to the secure email address (data@specmx-5.com), where data will be
reviewed by AiM directly. Failure to adhere to this guideline from the Series, or having non- functioning data, may be grounds for
penalty or disqualification by the Series.
a. Vehicle must be equipped with current generation AiM data acquisition system (configurable in Race Studio 3) that can provide
on track data to AiM race studio 3. The data acquisition system may only read the OBDII/ECU data stream. It is not permitted
to alter/manipulate data to and from the ECU. The AiM system may be utilized to trigger a switch I.E., cooling fans or diff cooler
pumps but must be wired via a separate analog circuit.
Refer to Section 17: Electrical Equipment above for installation requirements.
b. The connection at the OBDII port for the AiM system may be made in either one of two ways:
1. Through a dedicated OBDII AiM adaptor.
2. By direct wiring to the back of the OBDII port within 3” of the ODBII connector.
c. Fuel pressure datalogging is required.
d. Oil pressure datalogging is required.
e. All cars must run the latest AIM Data Logger Spec MX-5 ECU Protocol
21. Mandatory
Video
Camera
Cars running in Spec MX-5 must have a functioning video recorder/camera during all qualifying and race sessions as described in 9.3.11.
Upon request by an SCCA official, competitors must provide their video recording/data, which may be used by the SCCA for any
purpose including but not limited to rule enforcement and marketing. Failure to comply with a video request from an official, or
having a non-functioning video recorder/camera may will be grounds for penalty or disqualification.
22. Parts
Confiscation
a. Tech officials may confiscate competitors’ parts for the purpose of verification of tech compliance.
23. Penalties Clarification – Non-Compliant Parts
Level Infraction Penalty
1 Non-compliant modification to any of the spec
parts, engine components, ECU/Elec- tronics or
modification to the chassis.
May suspend the driver (i.e. suspend) of the non-
compliant Spec MX-5 from competing in SCCA
events for the 12 months following the suspension.
A level 1 infraction carries a $1,000 fine.
2
Non-compliant modification to the suspen- sion or
drivetrain outside of level one infrac- tions: engine,
fuel system, charging system, exhaust, and intake
system.
May suspend the driver (i.e. suspend) of the non-
compliant Spec MX-5 from competing in SCCA
events for the 6 months following the suspension.
A level 2 infraction carries a $500 fine.
3 Use of an unauthorized or non-compliant part,
engine component, ECU/Electronics or chassis or
chassis part.
May suspend the driver (i.e. suspend) of the non-
compliant Spec MX-5 from competing in SCCA
events for the 12 months following the suspension.
A level 3 infraction carries a $1,000 fine
4
Non-compliance (non-modification such as
incorrect part)Use of an unauthorized or non-
compliant for any of the suspension or drive- train
part or component outside of level one infractions:
engine, fuel system, charging system, exhaust, and
intake system.
May suspend the driver (i.e. suspend) of the non-
compliant Spec MX-5 from competing in SCCA
events for the 6 months following the suspension.
A level 4 infraction carries a $500 fine

Porsche 718 Cayman GT4 CS MR - Spec Line #4070: "315 DOT, 305/660 Non-DOT"
Porsche 718 GT4 RS Clubsport - Spec Line #4080: "315 DOT, 305/660 Non-DOT"
Toyota Supra GR GT4 - Spec Line #4090: "315 DOT, 305/660 Non-DOT"

w. Instrument clusters must be unmodified parts."

Valves IN & EX: "(I) 36.6/(1.44) (E) 28.7 29.7/(1.17)"

Notes: "(Effective 3/1/2025) 55mm 51mm Flat Plate Intake Restrictor is required."

BMW - Spec Line 1090:
Required Restrictor: "(2) X 40mm 35mm diameter hole inlet restrictor plate required"
Chassis Notes: "This spec line is set to expire 12/31/25."
BMW - Spec Line 1100:
Minimum Weight: "3150 3350”

9926, Eibach front sway bar 0000-04-5306-FT, Eibach rear sway bar 0000-04-5306-RR, Interior finish panels 0000-07-5822, C&R
radiator/oil cooler assembly 0000-01-5504-CR, Oil cooler adapter and lines 0000-01-5511-KT, ACT clutch 0000-02-5004-G6,
wheels 17x8 #0000-04-5706-GM, # 0000- 04-5706-SL, and Toyo RR 235-40-17 dry, Toyo RA1 235-40-17 wet. Alternative tires on
17x7 wheels per STL rules. No other Super Touring modifications or allowances permitted except as noted in this spec line. Must
conform completely to GCR 9.1.7.1, except alternative tires (only) per STL regs allowed."

is the competitor’s responsibility to ensure their tires are marked prior to going on track for the next session. A mandatory
impound for all SMX competitors will occur after the first dry qualifying or race session. All tires will be marked for the remainder
of the race weekend. It is the competitor’s responsibility to report to impound and ensure their tires are marked prior to leaving
impound.
3. If a competitor damages a tire or wheel, and there is a safety concern, the competitor must find the Hoosier Super Tour Series
Tech Chief or SMX CCC, if assigned, for inspection. At the direction of the Hoosier Super Tour Series Tech Chief or SMX CCC, the
compet- itor will be allowed to substitute alternate used tire(s) to replace the damaged tire(s). New tires are not an option as a
replacement tire for a damaged tire. If a competitor damages a tire or wheel and there is a safety concern, the competitor must
find the Hooseir Super Tour Series Tech Chief or SMX CCC, if assigned, for inspection. At the discretion of the Hoosier Super Tour
Series Tech Chief of SMX CCC the competitor may be allowed to substitute alternate used tires(s) to replace the damaged
tire(s). New tires are not an option as a replacement tire for a damaged tire."

from converting to rear disc brakes under this rule.
3. The “Brakes Std.” and “Brakes Alt.” listings on a vehicle’s spec line do not prohibit a car that was fitted with rear drum brakes
as stock from converting to rear disc brakes under this rule."

In EP Spec Lines, BMW Z3 2.5L, change Weight as follows:
"2500 2550
*2563 2614
**2625 2678"

**2373 2426"
Acura Integra GSR (92-93):
"2325 2375
*2383 2434
**2441 2494"
Honda Civic Del Sol VTEC (94-97):
"2290 2340
*2347 2399
**2378 2457"
Honda Civic Si (99-00):
"2250 2300
*2306 2358
**2363 2415"
FP Spec Lines, change Notes as follows:
Mazda Miata 1.6L (90-97): "Comp. Ratio limited to 10.0:1 11.0:1, Valve lift limited to .390” .425"."
Mercury Capri 1.6L (91-94): "Comp. Ratio limited to 10.0:1 11.0:1, Valve lift limited to .390” .425"."

Required Restrictor: "80mm"
Engine Notes: "An L76 is an LS2 block with LS3 intake manifold and heads. All parts must be OEM. May resleeve to stock
parameters for engine repair."
Spec Line # 1180
Required Restrictor: "75mm 78mm - Flat Plate"
Spec Line # 1190
Required Restrictor: "70mm 73mm - Flat Plate"
Spec Line # 1200
Required Restrictor: "72mm 78mm - Flat Plate"
Spec Line # 1201
Required Restrictor: "70mm 73mm - Flat Plate"
Spec Line # 1210
Required Restrictor: "72mm - Flat Plate"
Spec Line # 1350
Required Restrictor: "(2) 55mm 60mm flat plate"
Spec Line # 1370
Required Restrictor: "(2) 55mm 60mm flat plate"
Spec Line # 1390
Required Restrictor: "(2) 55mm 60mm flat plate"
Spec Line # 1420 "*Spec line Expires 12/23"
Required Restrictor: "52mm FPR"
Spec Line # 1429
Required Restrictor: "75mm - FPR"
Spec Line # 1460
Weight: "3500 3600"
Required Restrictor: "70mm - FPR"
Spec Line # 1480
Required Restrictor: "80mm FPR"
Spec Line # 1490
Required Restrictor: "75mm - FPR"
Spec Line # 1590
Engine Notes: "90mm Throttle Body Permitted"
Spec Line # 1595
Required Restrictor: "72mm – FPR"
Spec Line # 1596
Required Restrictor: "61mm 70mm – FPR"
Spec Line # 4120
Required Restrictor: "75mm flat plate"

Trans. Speeds: 5"
Fiat X-1/9 & Bertone:
"Fuel Injection
(1) 34 DMTR, (1) 36 DCNF w/34mm choke(s), or (1) 40DCNF w/34mm choke(s)
(1) 36 or 40 DCNF w/34mm choke(s)
(2) auto-type side-draft w/28mm choke(s) on I.R. manifold
Orientation of the alternate carburetor is unrestricted. The alternate carb adapter may not be thicker than 1.25”. The adapter
may have a bore larger than the throttle bore of the approved alternate carburetor.
Valve Size: (I) 35.5/(1.40) (E) 33.0/(1.30)
Trans. Speeds: 5 or 4"