This is confusing to me. I have read countless claims of GT40 heads and intakes with the stock HO cam putting down 270ish RWHP. That's pretty much all I am looking for is somewhere between 250 and 300 at the wheels. If the heads only get me to 200, I can't imagine the intake delivering another 70HP. Are all of these folks mistaken or just plain lying? Here I was getting my hopes up. Kind of disappointing when my 6 cylinder 4 door Pontiac is faster than My GT Mustang with mods. The Pontiac hasn't sold yet, maybe I should keep it.
The 95' Cobra, with the GT-40 heads, has a bigger intake, throttle body, and cam then the HO motor, and it has 245hp at the crank. Logic alone is going to tell you that putting those heads on a stock HO motor is not going to yield 270rwhp. When people are talking about putting down 270rwhp, they are talking about doing it with late model Explorer GT-40p heads. Probably heads that have been worked over quite a bit. The GT-40 name is used quite a bit by Ford, and there are many heads that have the GT-40 badge. The ones that came on Cobra cars suck nuts. There are the late model GT-40p heads that came off the Explorers, and at least two different performance aluminum heads; the GT-40 turbo swirl heads, and the GT-40x heads. The aluminum heads will definately get you to 270rwhp, but they cost as much as other performance aluminum heads that are better.
If you are looking for a budget H/C/I combo, get a set of Thumper Perforance E7 heads, and like a Trick Flow 1 camshaft. The cam is like $150, and you can get the heads from Thumper Performance for $699 I think. The heads are a bargain, they are fully ported and rebuilt. Who knows how much wear and tear the heads you got off a 93' Cobra have. You can pick up a late model Ford Explorer intake for about $100 on ebay, maybe a little more. You're going to have some nickel and dime items, like new lifters and a new timing chain, gaskets, etc. You will probably need to upgrade to 24lb injectors, which means a new MAF, or some sort of chip. If you get a decent size cam, you will need a chip anyway, so you might as well get the chip and skip the MAF. Thumper performance advertises combinations in excess of 300rwhp with these heads. I have become a fan of these budget builds, because the price of 5.0 parts has come down so much.