S&S Cams are tested on the dyno, street and track before being offered to the public. With hundreds of hours of testing on each cam, you know you are getting the best cam S&S can produce. For large displacement engines (110"+) with 10.5 to 11.5:1 compression and smaller engines (96-107") with 11 to 12:1 compression. Requires high-lift springs. Less overlap and fast ramps build higher cylinder pressure. Lower TDC lift makes installation easier. Designed for use with hydraulic tappets. Installer must check coil bind, valve-to-valve clearance, valve-to-piston clearance and cam lobe to case clearance.. Made in the U.S.A..