[tmoss]

The cam change may be worth it, but if you don't improve the GT40 heads with porting, no need to port the Cobra intake or change manifolds as the heads will be the limitation. After working/changing the heads, the Cobra lower can be ported to keep up with heads up to about 250cfm for a reasonable cost (~$130-140). No need to do extensive owrk to the upper either. Extrude Hone is a lot more expensive - $500 for both upper and lower or $250 each. 300cfm can be had from the Cobra if you want to pay for lots of welding and porting, but why? - just go aftermarket past about 250cfm.