LSX-LS7 CNC PORTED CYLINDER HEAD ASSEMBLY -19354241. LSX-LS7 CNC PORTED CYLINDER HEAD ASSEMBLY. Great cylinder head airflow is yours with Chevrolet Performance LSX cylinder heads. With power-building attributes, these aluminum heads are manufactured from 319-T5 aluminum alloy and assembled with premium lightweight hollow-stem valves, sodium-filled exhaust valves and–on some models–titanium intake valves. Ensure maximum airflow and exceptional performance with Chevrolet Performance LSX cylinder heads. LS7-style rectangle port design. Assembled with 2.200″ titanium intake and 1.610″ sodium-filled exhaust valves. 12° valve angle; minimum 4.100 bore. 70-cc “as-cast” combustion chambers. 650 lift with premium springs. Uses LS7 rocker arms/LS7 bolts. Uses P/N 19257879 bare head (shown).