Great low and mid-range torque, Strongest from 1000-4500 RPM, Bolt-in cams for 88 CID engines with stock compression ratios, 180 psi cranking compression; no need for compression releases, Lower lift allows them to be bolted into stock 96"-106" '06 engines with stock valve springs, Cams for '00-'06 Twin Cam are for use with stock splined drive gears; for installation on '99 Twin Cam motors you must purchase splined outer drive socket; S&S recommends that Andrews 4340 steel drive sprocket to be used., Made in the USA, Installer must check coil bind, valve to valve clearance and valve to piston clearance.