Muscle Head Stage II “Pro Mod / Big Port / Big Throat”: Program #04, 2.450″ x 1.900″ valve dia, 97cc chambers. Std Copper valve seats, .025″ Jr hoops, All 9/16″ Head stud inserts. (pair)

Muscle Head Stage V: Program V3-P3-F12, 2.400″ x 1.900″ Valve dia, 102cc chambers. Std Copper intake valve seats, B5 Exhaust valve seats, .025″ Jr Hoops, 5/8″ Top Row & 9/16″ Bottom Row Head stud inserts. 2.600″ lifter spread, 12ø Exhaust Flange. (pr)