Cylinder Heads:. High-flow cylinder heads with premium seats, guides, valves, springs, and seals. +1.00 mm oversized intake and exhaust valves. Valves are 0.030" longer than stock for improved valvetrain geometry. 0.605" max lift valve spring. 550G gear drive cam. Enlarged cooling passage around the exhaust seats. S&S exclusive breather boxes. Crankcase:. Patented dual-spray piston cooling jets. Precision machined oil scraper. Enlarged oil sump. Contoured floor allows oil to easily drain back to the sump. MK136:. Retains stock engine height. Includes forged pistons, S&S performance oil pump and cam support plate, premiun tappets and tappet cuffs, billet aluminum covers, sprocket shaft spacer, Champion spark plugs and cam cover badge. Made in the USA.