EngineQuest EQ-CH364AA Cylinder Head 69cc Cathedral Port Head for GM LQ4 317 6.0LGM LS 6. 0L Cylinder Head 69cc Cathedral Port Cylinder Head Assembled 2. 000 in 1. 570 in Valves 211 cc Intake 71 cc Chamber Aluminum GM LS Series Each All EQ cylinder heads outperform their competitors! Thicker deck for greater strength Improved design resists cracking Superior port finish for increased flow Water flow redesigned for greater thermal conductivity Hardened exhaust seats CNC machined guides and seats 25 point quality check on every head