Pro Action™ GM LS3 Rectangle Port Aluminium Cylinder Heads feature:

• Same architecture as factory head - all stock components will fit without issue
• Factory correct intake manifold alignment slots avoid power robbing misalignment
• Manufactured with premium materials and machined to industry's tightest tolerances
• Premium bronze/manganese valve guides for long wear with particular emphasis placed on holding precision tolerances on valve seat concentricity, allowing valve to seal securely for more power
• Clean Cast Technology eliminates casting laws and promotes a smoother internal surface finish for greater air and coolant flow
• Dual seat spark plug pocket design allows both factory style tapered seat spark plugs and flat seat style plugs in wider heat ranges
• .660" Lift springs allow for higher lift cams and increased RPM
• Designed for any LS3-style street performance application