Greddy Rocker Arm Stoppers Nissan SR20DET S13. Helps prevent valve float on all S13 SR20DET engines. A must for use with aftermarket camshafts, or any SR20DET reving past 7400 RPM. A small price to pay to prevent a bent valve. Rocker floating at high rpm is among one of the main concerns with the SR20DET. When this occurs, RAS keep the rockers in their place to prevent rockers from flying out which might lead to severe engine damage. * Kit specific for S13 SR20DET ONLY. Machining needed for S14