We were first to market with a conical valve spring kit for Gen V LT4s. Big whoop, right? WRONG. Weight is the enemy of a proper functioning valvetrain. If your cam isn't too radical, a dual spring kit isn't required. These springs will vastly improve valvetrain stability at high RPM while still supporting up to .650" lift. Made right here in the good ole US of A, this kit includes springs, locks, seals and locators. Uses stock retainers. LT1/L86 engines require SK013.