So i Have a 94 GT. I wan to change the heads out. Which Heads between the GT40 And The GT40P are better, and which one will add more HP? If you know why one adds more than the other, feal free to tell me why also..
Thanks
I personally would go for the standard GT head, that way you don't have to get new headers along with it. They are within a few hp of each other performance wise so the choice is really up to you.
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The Explorer GT40P and Cobra GT40 heads have almost identical intake port flows but the GT40P outflows the GT40 on the exhaust side, and therefore makes more HP. The downside of the GT40P is that the spark plug holes are at an awkward angle and require the use of special "P" headers to fit (MAC Performance have them). The GT40 heads retain the stock plug hole position and allow a wider choice of headers to fit.
The Explorer GT40P and Cobra GT40 heads have almost identical intake port flows but the GT40P outflows the GT40 on the exhaust side, and therefore makes more HP. The downside of the GT40P is that the spark plug holes are at an awkward angle and require the use of special "P" headers to fit (MAC Performance have them). The GT40 heads retain the stock plug hole position and allow a wider choice of headers to fit.
if i ported the exhaust side more on the gt40, would it match the gt40p? and would this be a ideal way to go with heads or just go to something eles. what is better than the gt40 or gt40p heads, thats caust about the same price range?
You can get some World Products heads, complete, for around $650-$700 and will murder the GT40/P heads.
Porting on just about any head will improve it, the P head has a slightly better exhaust design so it's a trade off. A couple extra hp but new headers, or a couple horsepower less and less hassle. The difference isn't like 20 hp, it's like 5-7 between the two.
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gt40. for all the above stated reasons. go ahead and change the cam & timing chain set while you're there. a good cam matched for your application will really make a noticeable difference when you mash the go pedal. the grin factor will increase as well.
looky here--scroll to the bottom of the page and look at the "average airflow" column
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GT 40 or GT 40P Heads? 1994 Mustang GT 
