Reverses the rear cam's direction of rotation, providing additional operating clearance between cam lobes, making higher cam lifts possible. Increase valve timing accuracy by eliminating timing chain lash and loosely fit stock chain. Provides strong low end torque and horsepower. Strongest from 1500-5000 rpm. Material must be removed from inner surface of the stock gear cover to install. A hydraulic press and other professional level tools are required for installation. Cam bearings and gaskets must be replaced. S&S recommends that adjustable pushrod/cover kit be used (sold separately). Kit includes camshafts, inner gears, outer drive gears, inner, outer bearings, gasket and instructions. Made in the USA. Due to inherent characteristics of gear drives, more valve train noise maybe heard.. Installer must check coil bind, valve to valve clearance and valve to piston clearance.. Not recommended for engines having compression ratios greater the 10.1:1.