KIBBLEWHITE Spring Kit .660″ Evolution/Twin Cam 20-21500

Stainless steel conversion kit includes only what’s needed to convert your head to the long-life stainless steel Black Diamond intake valves, Extend the life of the valvetrain and intake components by as much as 4x over the OEM titanium parts, Includes forged one-piece stainless steel intake valves, wound chrome-silicon heat-treated wire valve springs, ultra-light titanium retainers and hardened steel bases, Components are created using Finite Element Analysis (F.E.A.) software, as well as proprietary camshaft analysis and spring design software, Specifically designed and engineered for each application, Made in the U.S.A.