use recommended springs to match your camshaft - Exhaust flange is extended .300" from stock (same as Mopar Stage 6) featuring dry exhaust bolt holes with Heli-Coil thread inserts - Max Wedge intake ports are machined to match intake manifolds for B and RB competition big-block Chryslers - 72cc combustion chamber volume - Cylinder head part #77949 comes bare with valves only