TRICK FLOW SHALLOW CHAMBER LS1 FAST AS CAST CYLINDER HEADSTrick Flow GenX 220 cylinder heads for LS engines are the best value in GM LS performance. These cathedral port heads incorporate features of Trick Flow's fully CNC ported LS heads such as 13. 5 valve angles, decreased valve shrouding, increased mid lift airflow, relocated spark plugs, CNC profiled combustion chambers with port to valve seat blending (bowl blending), improved rocker arm valve cover clearance, 50 exhaust valve job, and rigid casting