Complete Heads are assembled with Stainless Steel 40mm Intake and 35.5 Exhaust Valves, Single or Dual Hi-Rev Valve Springs, Chromoly Retainers and Hardened Keepers. Available with 12mm 3/4" reach plug. Stock size ports. All EMPI Complete Heads are supplied with Stainless Steel Valves. Lash Caps P/N 4006 are required in all cylinder head applications that have Stainless Steel Valves.