Bolt in cams for 88 CID engines with stock compression ratios. Increases valve timing accuracy by eliminating timing chain lash and loosely fit stock chain drive. Reverses the rear cam's direction of rotation, providing additional operating clearance between cam lobes; resulting in higher cam lifts that are possible with the gear kit. Material must be removed from inner surface of the stock gear cover to install. S&S recommends that adjustable pushrod/cover kit to be used. Cam bearings and gaskets must be replaced when installing new cams. Lowers loft allows cams to be bolted into 96"-106" '06 engines with stock valve springs. Strongest from 1000-4500 rpm. 180 psi cranking compression; no need for compression releases. A hydraulic press and other professional level tools are required to install. Kit includes cams, inner gears, outer drive gears, inner and outer bearings, gaskets and instructions. Made in the USA. Installer must check coil bind, valve to valve clearance and valve to piston clearance.. Due to the inherent characteristics of gear drives, you may experience more valve train noise..