Designed as bolt-in cam for 05-13 touring bikes with compression ratio between 9:1 and 9:9. More power across the rpm range, with improved low and midrange torque. Can be used with stock pushrods, springs and lifters. Strongest from 0-4,000 rpm. 99-04 models require high lift springs. Cams for 06 Dyna and 07-13 Twin Cam are for use with models with hydraulic tensioner chain-drive system; 551C are bolt-in applications,. all others require high-lift valve springs. Intake Opening (degrees): 18. Intake Closing (degrees): 20. Exhaust Opening (degrees): 39. Exhaust Closing (degrees): 15. Intake Duration (degrees): 215. Exhaust Duration (degrees): 237. Valve Lift (in): .550.