ACT's WRX and STi Performance Street (SS) friction surface is SFI certified and is an excellent choice for modified, street driven cars. The SS disc provides quicker engagement than a stock surface and is quiet compared to other, more aggressive friction surfaces. The SS disk is available coupled to the Heavy Duty pressure plate for a 41% increase in clamp load, or the Xtreme pressure plate which increases the clamp load by 57%. ACT's Performance Street disk uses a sprung hub with bushings and cone springs similar to OEM clutch discs; creating frictional dampening that improves clutch life and reduces noise. The SS kit is suggested as a stock replacement or for light to moderately modified WRXs.