Designed specifically for S&S® T-Series T2 long block engines for Harley Davidson® big twins and engines with S&S® 4-1/4'' bore Hot Set Up installed2.000'' intake and 1.605'' exhaust valves coupled with S&S® ports, supply plenty of air for these big motorsS&S® High performance valve springs allow the installation of camshafts with up to .650'' liftCompatible with stock rocker boxes, exhaust, and intake manifoldsManifold mounting surface is machined to stock dimensionsMade in the USAA special manifold/throttle body is required for engines that are not stock height.Not machined for compression releases.Must use S&S valve cover gasket kit with stock rocker covers.Not compatible with '14-'16 FLHTK/FLHTKL, FLHTCUTG Twin-Cooled motors or '17 touring models.