The .551 inch lift cam is designed for engines with 96 to 106 CID and 9:1 to 10:1 compression this is a bolt-in cam set designed for stock or mildly modified touring bikes. Greatly improves low-end and midrange torque, strongest from idle - 4000 rpm. S&S chain drive cams are a great way to increase performance at an affordable price, are installed in a short period of time reusing many stock components.