Built for the (02-05) Subaru WRX... Most stock flywheels are heavy cast iron parts designed for optimum street driveability by soaking up some of the power from the engine and putting it in storage in the form of inertia. Although this may be important for transporting the groceries, this driveability comes at the expense of engine response and acceleration. Light weight flywheels keep less inertia in storage but the lighter rotating mass provides significantly improved engine response and acceleration characteristics. Until now most aftermarket flywheels for sport compact vehicles presented certain undesirable concessions to the user. Many are too light or fragile for the application, others have reliability issues and all are very expensive.Finally, ACT offers exactly what performance enthusiasts need: all the benefits of a premium quality light weight flywheel at an affordable price.ACT currently manufactures XACT flywheels in two versions, ProLite for road racing applications and very quick throttle response, and slightly heavier StreetLite for street and drag racing vehicles which may require more inertia. For example, the Integra ProLite weighs 8.8lbs and the Integra StreetLite weighs 12.5lbs. Both ProLite and StreetLite flywheels are precision made from Chrome-moly forgings and feature an induction hardened integral ring gear. All ProLite and StreetLite flywheels are CNC machined, heat treated for strength and precision balanced. Substantial material is left behind the clutch surface area for better heat dissipation and durability while weight savings is made where it matters the most for reduced inertia.XACT flywheels are certified by ACT to meet SFI Spec. 1.1. This makes XACT Flywheels legal for competition when SFI Spec. 1.1 is required or recommended. XACT flywheels come complete with official SFI sticker and serial number as required for certification.