Reduces total valve train mass. Great for racing high lift performance builds. The springs are manufactured from the highest quality clean chrome silicone wire, shot peened and heat treated for maximum fatigue life. Kit includes springs, upper collars, lower collars, and valve keys. Max valve lift: .480". Installed height: 1.310". Seat pressure 158 lbs. Open pressure: 340 lbs. @ .480" valve lift. Note: Kit must be used with Kibblewhite Precision engineering (KPMI) valve guides. Stock dimensions valve guides must be shortened. Valve guide machining instructions are included with this kit.