These S&S® Super Stock® high performance cylinder heads are designed specifically for early production S&S® T124 engines for 1999-'06 HD® big twins. Heads are machined for the S&S® cylinder stud pattern used on S&S® Special Application crankcases. 2.000" intake and 1.605" exhaust valves coupled with S&S® ports, supply plenty of air for these big motors. Machined for S&S® electric or manual compression releases. The manifold mounting surface machined to stock specifications so special length manifold/throttle body is required for engines that are not stock height. 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.