These S&S® Super Stock® high performance cylinder heads are designed for 1999-'05 engines with stock crankcase. They work well with engines of stock displacement , but are ideal for somewhat larger stroker or big bore engines up to 110". The 89cc combustion chamber provides a slightly higher than stock, but still manageable compression ratio in larger than stock engines. This makes them a good choice for touring bikes and other heavy vehicles. The large 2.000" intake and 1.605" exhaust valves maintain port velecity for good low and midrange response, but supply enough air for slightly larger engines to perform to their full potential. S&S® High performance valve springs allow the installation of camshafts with up to .650" lift. Intake ports flow 264 cfm compared to stock heads at 182cfm. S&S® High performance valve springs allow the installation of camshafts with up to .650" lift. Compatible with stock rocker boxes, exhaust, and intake manifolds. Black wrinkle powder coat finish matches stock black engine components.