The biggest hindrance to performance with the Cross-Fire engine is the intake. Chris improves the intake by removing the diffusers under the throttle bodies and enlarging the holes in the intake cover. Also, the bottom end of the ports are very restrictive, and Chris opened them up to match the size of the ports in the heads. In the photo, the area from Chris finger to the top of the port was initially filled with casting. With the porting finished, the heads were Extrude Honed for maximum flow.