GT40-p or GT40-x

I just blew a head gasket on my car and have a friend that has a set of gt40-p's and gt40-x's that i can get from him. My question is which are better and why? I do have a turbo setup and the headers on the car now are not forgiving, and i had to notch the exhaust pipe coming from the turbo down so i could get the plug wire on the sparkplug. I think that the P heads move the sparkplug to a different location, to fire in the middle of the piston. Thanks for all of the help.
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10 Year Member
Oct 31, 2006
Chengdu Province
The X is the better head, and yes, the Ps usually require a special header. Watch the combustion chamber volume, I believe the Xs came in two different sizes, one being 58cc, which will raise your compression ratio if you're running stock heads right now.


I want to measure mine. It doesn't look that tall.
15 Year Member
Jul 6, 2006
X's are aluminum and wont require special headers. The p's are iron heads. unless you the p's are basically free I dont see why picking them is a logical choice.