ACT XT/Perf Street Sprung & HD/Race Sprung 6 Pad Clutches Celica GT4 3SGTE. TC4-XTSS kit features an Xtreme pressure plate for the most demanding driver. ACT Xtreme 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 have reduced marcel for faster shift action to complement ACT pressure plates. Quiet operation with increased strength and reliability. Feel: Moderate to heavy pedal effort, smooth engagement, OE to mild gear rattle; Life: Longer friction life, extended by ACT's exclusive diaphragm design; Quality: Carefully engineered, precisely assembled, accurately balanced, with premium organic friction materials for heat tolerance and reduced fade; Recommended Use: Recommended for street and race use; ACT Difference: 100% clamp load tested and dynamically computer balanced for smooth high RPM reliability. TC4-HDG6 kit features ACT's most popular Heavy Duty pressure plate. 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 6-pad, spring-centered race disc features a spring-center to properly damp torsional vibrations and resist failure under harsh conditions. ACT spring retainers utilize wraparound spring windows and thicker retainer stampings to provide spring support, reduce stress concentrations, and increase strength and reliability. With the 6-pad, spring-centered race disc, engagement is harsher, but shifting is faster. The 6-pad, spring-centered disc is recommended for larger clutch sizes to absorb more heat. Feel: Light to moderate pedal effort, aggressive engagement, OE to mild gear rattle; Life: Moderate friction life, extended by ACT's exclusive diaphragm design; Quality: Carefully engineered, precisely assembled, accurately balanced, uses select ceramic friction materials for high heat tolerance and maximum performance; Recommended Use: Recommended for high horsepower street or race use; ACT Difference: 100% clamp load tested and dynamically computer balanced for smooth high RPM reliability.