Bolt-in 100 HP cam. Compatible with all stock components but requires free-breathing air filter & exhaust mufflers. With each cam change S&S recommends their 583903 Precision tappet assembly set. Kit includes cam; all required bearings; o-rings and hardware. Gear drive cams provide improved valve timing accuracy but more mechanical sound; when compared to chain driven cams. The additional mechanical sound is the reason why OEM runs chain driven cams. Note: For best performance it is; like with all performance cams; recommended to use a free breathing air cleaner and exhaust system. Note: With each cam change S&S recommends their 583903 Precision tappet assembly set. Note: See the printed or online Motorcycle Storehouse catalog for the S&S camshaft specification chart.