These S&S Super Stock high performance cylinder heads are designed for 2006-2017 Twin Cam engines with stock cylinder head pattern. These ported heads with larger than stock intake and exhaust valves are great for stock 88CI through 110CI motors, including Big Bore and stroker applications. The 89cc heads, for example, have a 45% higher flow rate than stock heads. Heads come in pairs and ready to install with valves, valve guides and valve springs for use with up to .650" lift cams in place. Also included are four longer than stock cylinder head bolts, the other four are to be re-used from the original engine. Kits can be installed with stock rocker boxes with the included S&S rocker base gaskets and are compatible with stock manifolds and stock or stock-replacement exhausts.