The Manley Performance Valve Spring and Retainer Kit has been designed to accommodate high-lift cams, and to allow users to surpass OEM rev limitations when power levels have been increased from built motors, larger turbochargers, aggressive cams, or ported heads. Basically if you plan on drag racing, time trials, or any form of spirited driving where the engine lives in the upper- RPM range then upgraded valve springs are a must.

The Manley Performance Valve Springs and Retainers are fabricated from high grade steel, and the max net lift is 0.510”