2004-2021 Subaru STI ACT XACT Prolite Flywheel 600240 is a Prolite flywheel, which is ACT\’s lighter flywheel offering with lowest inertia. Prolite flywheels are designed for best throttle response and acceleration. Prolite flywheels are preferred for road racing or rally racing, and have reduced drivability. Materials are properly distributed for maximum strength, good heat tolerance and rigidity. ACT flywheels are serviceable and can be resurfaced with no need to purchase additional parts. Features Dramatically improved engine response and acceleration, mild to moderate gear rattle Heat-treated forging for strength and toughness, induction-hardened ring gears for maximum life One piece construction allows less opportunity for failure and provides uniform efficient heat transfer from the clutch disc. No more warped inserts or loose ring gears Recommended for race use Forged, CNC machined and dynamically computer balanced for smooth high RPM reliability Benefits Designed for best throttle response and acceleration Materials are properly distributed for maximum strength Good heat tolerance and rigidity Applications 2004-2021 Subaru WRX STI 2007 Subaru Legacy GT spec.B (6-Speed) What\’s in the box? 600240 – XACT Flywheel Prolite PB1004 – Pilot Bearing Installation Instructions!