Tech Bulletins for GT2 and GT2-ST
#39537 from Grand Touring Committee · Rule change · TB 26-01 (2026-01 Fastrack)
In GT2 Spec Lines, GT2 Cars – Porsche, classify 992.1 GT3 Cup as follows:
GT2 Cars – Porsche
Model Year Body
Style Driveline Wheel Base Notes
992.1
GT3 Cup
(22-25) 2 Dr RWD 4.0L flat six. 3250lbs. w/60mm Throttle Body Restrictor (TBR).
Cars must be prepared in accordance with the appropriate
Show 49 more lines
model/year Porsche factory 911 GT3 Cup parts
catalog/service manual. Cars may not be altered in any way
except as authorized below. Drivers must have the correct
year manuals as they apply to their specific car in their
possession. Safety, drivers comfort, driver control and
instrumentation items may be modified per the GCR. Original
factory installed Matter/ IMV roll cages are allowed. The
stock unmodified fuel tank is allowed. Windshield clips must
be installed per GCR 9.3 Windshield Clips/Rear Window
Straps. All other SCCA safety standards apply. Tires per GCR
9.3 Tires. Lubricants, consumable fluids (brake fluid, coolant
etc.) and oil filters are open free. Factory (OEM manufacturer)
Lexan front windows allowed as delivered. ABS is allowed.
In GT2 Spec Lines, GT2 Cars – Porsche, change Notes as follows:
991.1 GT3 Cup: "3.8L flat six. 3000lbs. w/72mm Throttle Body Restrictor (TBR). Aftermarket header allowed."
991.2 GT3 Cup: "4.0L flat six. 3000lbs. w/65mm 70mm Throttle Body Restrictor (TBR)."
997.2 GT3 Cup: "3.8L flat six. 2900 2800 lbs. Aftermarket header allowed."
In GT2 Spec Lines, GT2 – ST, Chevy Corvette (-2013), change as follows:
5665:
Restrictor: "81 85mm flat plate"
Notes: "GM LS1, LS6. LS1/LS6 C6 Corvettes using the OEM C6 intake manifold and 90 mm throttle body must use a 78mm flat
plate restrictor. OEM 75mm throttle body and manifold do not require a restrictor. LS6 may reduce weight by 50 lbs. L S1/LS6
alternate intake manifold, DORMAN part # 615-900."
LS2 5967 Restrictor: "83 85mm "
L76 5967 Restrictor: "80 83mm flat plate"
LS3 6162 Restrictor: "80 83mm flat plate"
6162 GM LS3:
Weight: "3250 3150"
Restrictor: "74 80mm flat plate"
6162 GM LT1:
Weight: "3250 3150"
Restrictor: "74 77mm flat plate"
In GT2 Spec Lines, GT2 – ST, Chevy Corvette (14-19), change as follows:
5665:
Restrictor: "83 85mm flat plate"
Notes: "GM LS1, LS6. LS1/LS6 C6 Corvettes using the OEM C6 intake manifold and 90 mm throttle body must use a 78mm flat
plate restrictor. OEM 75mm throttle body and manifold do not require a restrictor. LS6 may reduce weight by 50 lbs. L S1/LS6
alternate intake manifold, DORMAN part # 615-900."
LS2 5967:
Weight: "3100 3000"
Restrictor: "83 85mm flat plate"
L76 5967 Restrictor: "80 83mm flat plate"
6162 Restrictor: "80 83mm flat plate"
6162 LS3:
Weight: "3200 3100"
Restrictor: "77 80mm flat plate"
6162 LT1:
Weight: "3200 3100"
Restrictor: "74 80mm flat plate"