CNC-Ported CID, 6-Bolt, LT4 Cylinder Heads, Assembled

Our CNC-ported GM LT heads are pretty darn good. These CID heads are better and by a lot! Here's why:  We buy these heads as porter castings which allows us to impart whatever design we like to the runners and combustion chamber. These heads were designed from ground up for competition, not transportation They are made in the USA using premium aluminum alloy with no  remelt under the watchful eye of CID's owner The deck is about 0.25 inch thicker than OE heads The six-bolt design provides a lot more clamping power if paired with a six-bolt block.  These are pretty rare now but should be coming from the usual suspects in the foreseeable future. We know what makes power and also survives the beating of competition.  It's not chasing peak air flow at max lift by excessively cutting away the metal around the valve guides. Peak air flow occurs at only one instant in the cycle. Our focus is more on average air flow across the entire cycle. For spring packages with 0.650 inch max-lift, qu