Designed for 1996 LT4 (or) 1992-97 LT1 small-block Chevy engines, RPM Xtreme LT4 cylinder heads are CNC ported in critical areas for improved airflow and peak performance. Features include high-quality 8mm stem stainless steel intake and exhaust valves that feed the high flow intake and exhaust ports. The highvelocity intake and exhaust runners are CNC ported in the bowl area and the intake entries and exhaust exits are CNC profiled for increased air-flow. Combustion chambers are fully CNC machined for absolute consistency and combustion. High-quality conical beehive springs are secured with titanium retainers and valve locks for performance up to .600" valve lift. RPM Xtreme LT4 heads are equipped with guide plates and 8mm stem valves, adjustable (non self-aligning) rocker arms are required. Match with RPM Air-Gap intake 350-7109, throttle body 350-5210 and camshaft 350-2108 for the Total Power Package combo.