Supertech Dual Valve Spring and Retainer KitOur valve springs are computer designed to ensure that wire stress levels do not overpass the limits of stress defined in the diagrams of fatigue. We also utilize computer software that allows us to ensure that the harmonics are under control. All Supertech valve springs are made with premium super clean Chrome Silicon Vanadium Steel alloy for higher performance & durability at high rpms. Using high quality steel alloy also provides the added benefit