Exedy Lightweight Flywheel 2004-2014 Subaru Impreza WRX STI H4

Lightweight flywheels reduce rotational mass in the engine which means more horsepower, and faster revvs. The Exedy lightweight flywheel combines low weight, low inertia, and high thermal capacity. Can be used in all different types of motorsports whether it be drag racing, rally, road racing or autocross. These could also be suitable for regular street use. 

These are constructed from a solid-one piece billet chromoly steel forgings, and improves the engine response. Other special design features include airflow design enhancements to improve the cooling of the clutch. The ring gear teeth are integrated onto the flywheel unlike an aluminum flywheel where the ring gear is pressed onto the flywheel which has the possibility of separating from the flywheel due to the different expansion coefficients of aluminum versus steel.