Super stock heads and crankcase S&S easy start cams High-flow oil pump Forged flattop pistons Intake system not included; compatible with stock or aftermarket intake systems 4-1/8 bore x 4-1/8 stroke 9.8:1 compression ratio Wrinkle black finish Cylinder heads on T-Series long block engines are 99-05 style. Owners of 06 models will need to purchase a set of 99-05 style, offset intake flanges. Cylinder heads on these engines are specially machined to compensate for the non-stock cylinder length. As a result, they are compatible with manifolds and throttle bodies with stock length intake runners. In addition, the breather vent bolt locations have been adjusted so they are in the stock location, so stock style air cleaner back plates will bolt up to these engines.