Designed for 88/96/103/110 cubic-inch engines with compression ratios from 10.0:1 to 10.5:1. Reverses the rear cam's direction of rotation, providing additional operating clearance between cam lobes making higher cam lifts possible. Increases valve timing accuracy by eliminating chain lash and loosely fit stock chain drive. Material must be removed from inner surface of the stock gear cover to install. 3500-6000 rpm for 88" to 103" engines and 2500-5500 rpm for larger engines. A hydraulic press and other professional level tool are required for installation. S&S recommends that adjustable pushrod/cover get be used. Cam bearings and gaskets must be replaced when installing new cams. Kit includes camshafts, inner gears, outer gears, inner bearings, outer bearings, gasket and instructions. Installer must check coil bind, valve to valve clearance and valve to piston clearance.. Due to the inherent characteristics of gear drives, more valve train noise may occur.. Made in the USA.