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. Works well in large-displacement engines 9.5:1 to 10.5:1 compression. Works with hydraulic or solid tappets. Makes best power in mid-range. Requires high-lift springs. Made in the USA. Installer must check coil bind, valve-to-valve clearance, valve-to-piston clearance and cam lobe to case clearance..