Are the gt40p heads much better then the gt40 heads? is it worth the bother cause of the exhaust manifold having to be changed, Does the intake also have to be changed to run the gt40p heads on a 1994 f150 5.0?

 

There are several types of GT40 heads. The 'P's were an improvement over the original cast iron GT40's but the newer aluminum Ford Racing GT40'X' heads are the best of all of them. The 'P's definately will create spark plug angle/header clearance issues, which can be worked around, but isn't worth it, IMO. If you are buying heads, go right for the 'X' heads. As for the intake, I am sure you can get away with using the original, but I'm thinking it would be silly. With a nice set of heads on that motor, you'll definately want a nice set of shorties and a new manifold. The real question I would have (and I am not sure of the answer) is whether or not you'll need to do a MAF conversion in order to get it tuned correctly.