Single mass flywheel conversion. Can be used with both factory clutch kit and ACT clutch kits. Gear rattle is expected. Noticeably improved engine response and acceleration, OE to mild 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 street and race use; Forged, CNC machined and dynamically computer balanced for smooth high RPM reliability 600591 is a Streetlite flywheel, which is considerably lighter than stock and is the most durable flywheel offering from ACT. Materials are properly distributed for maximum strength, lower inertia, good heat tolerance and rigidity. ACT's Streetlite flywheels are preferred for street or drag racing. ACT flywheels are serviceable and can be resurfaced with no need to purchase additional parts.