The SB9-HDSS kit features ACT's most popular Heavy Duty pressure plate and most popular street disc. ACT Heavy Duty pressure plates use exclusive diaphragm design to increase clamp load, reduce deflection and maximize clutch life. All diaphragms endure a four-stage, heat-treating process for unparalleled performance. ACT pressure plates have precision cover stampings to provide rigidity and consistency. ACT's Performance street discs are the most popular disc purchased. They feature premium organic materials with high copper content for better heat transfer and steel-backed lining for greater burst strength and durability. These discs feature a reduced marcel for faster shift action to complement ACT pressure plates. Quiet operation with increased strength and reliability. Monoloc is a one-piece, direct replacement or upgrade to the standard, two-piece wedge collar and wire ring featured in pull-type clutches. The spring tension of the segmented retaining ring is carefully calculated and tested for optimal performance. It provides uniform loading on the bearing and pressure plate to assure proper alignment, regardless of driver influence or vehicle modifications. Monoloc's hardened chrome-moly steel construction will provide years of service. Early Model 02 WRX Fitment: If your WRX was manufactured 6/2001 or earlier, this clutch kit will only work with an 03-05 ACT or OEM Flywheel