Parts and stages

From src/game/sim/partList.ts and src/game/sim/upgrades.ts. Each part’s full effect is at Stage 5; a lower stage gives its strength’s share. Each class gets its own share of every upgrade, sized so full builds land in the class’s band of times (CLASS_FACTOR in sim/specs.ts, checked by npm run bands:check): S 84%, T 78%, P 60%, H 62%. What each lever does: tuning.

Stages

Every non-single part is bought in stages. Its effect is stage strength × the part's full effect, its price cost × stage price × class price.

#	Stage	Strength	Price ×
0	Stock	0	0
1	Stage 1	0.4	1
2	Stage 2	0.5	1.6
3	Stage 3	0.65	2.5
4	Stage 4	0.8	4
5	Stage 5	1	6

Intake

Part	Stage 1 cost	Full effect	Notes
Cold-Air Intake coldair	250	hp 3%
Throttle Body throttle	300	hp 3%
Intake Manifold manifold	500	hp 5%, lowEnd -2%

Exhaust

Part	Stage 1 cost	Full effect	Notes
Long-Tube Headers headers	600	hp 5%
High-Flow Cat cat	300	hp 2%
Cat-Back Exhaust catback	600	hp 3%

Engine

Part	Stage 1 cost	Full effect	Notes
ECU Tune ecu	400	hp 5%, boostScale 25%
Camshafts cams	800	hp 5%, revRange 8%, lowEnd -5%	stage at most 2 above internals
Ported Heads heads	1,500	hp 10%
Stroker Kit stroker	2,500	hp 8%, tq 4%	stage at most 2 above internals

Support

Part	Stage 1 cost	Full effect	Notes
Fuel System fuel	400	none
Forged Internals internals	2,000	none

Boost

Part	Stage 1 cost	Full effect	Notes
Turbo Kit turbo	4,000	turboGain 60%	not with supercharger, stage at most 2 above fuel and internals
Twin-Screw Supercharger supercharger	5,000	superGain 40%	not with turbo, stage at most 2 above fuel and internals
Intercooler intercooler	600	boostScale 10%	requires turbo or supercharger
Boost Controller boostcontrol	200	boostScale 20%	requires turbo or supercharger
Water-Methanol Injection methanol	700	boostScale 10%	requires turbo or supercharger

Driveline

Part	Stage 1 cost	Full effect	Notes
Gearbox and Clutch gearbox	1,500	none
Limited-Slip Differential lsd	900	grip 8%	nothing on AWD

Traction

Part	Stage 1 cost	Full effect	Notes
Drag Tyres tyres	300	grip 70%
Drag Suspension suspension	800	squat 30%
Traction Bars tractionbars	300	squat 15%
Lightweight Wheels wheels	600	mass 1.5%

Weight

Part	Stage 1 cost	Full effect	Notes
Interior Strip interior	200	mass 4%	single
Carbon Hood hood	800	mass 1%	single
Lexan Windows lexan	600	mass 1.5%	single
Carbon Doors and Trunk carbonpanels	2,500	mass 1.5%	single

Nitrous

Part	Stage 1 cost	Full effect	Notes
Wet Nitrous Kit nitrouskit	800	none	single
Direct-Port Nitrous dualport	2,000	none	single, requires nitrouskit
Nitrous Reserve (1 bottle) reserve1	400	none	single, requires nitrouskit
Nitrous Reserve (2 bottles) reserve5	800	none	single, requires reserve1
Nitrous Reserve (3 bottles) reserve7	1,200	none	single, requires reserve5