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THRAMP-master
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Discussion Starter · #1 ·
What's the deal with headers for GT-40P heads? I've heard you need special headers, due to the spark plug location; however, the stock heads also have angled plugs. So, do I really need to find GT-40P headers for use in the FFR, or will standard 5.0 headers work?
 

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Ford Motorsport now makes a new header that's compatible with both plug angles - stock and the GT40P's. Mac makes a header that's decent, but I think the Ford header is better quality. I have the Mac version.

The plugs are not as angled on the GT40P heads. They stick out much straighter and require the primary tubes to start bending farther away from the head.

I've heard of people denting headers to make them work, but this hurts exhaust flow significantly, which defeats the purpose. Burned and cracked spark plug boots will be a problem too.
 

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Senior Charter Member
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I am currently using the stock configuration MAC header. I did slightly dent the #1 and 2 primary to clear the spark plug. I have also wrapped the headers in exhaust wrap. I personally don't think the reduced flow is much of a problem. I only dented about .250" maybe. I think the car runs just fine.
Thanks
Buzz
Ps
I can always spring for headers later, if necessary.
 

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THRAMP-master
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Discussion Starter · #5 ·
Thanks all.
 

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FFCobra Fanatic
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I've got the MAC P-headers and am pertty satisfied with them. The welds were good and the flange required no milling. However watch which gaskets you get as I had to modify mine to clear the spark plug hex.

Ben
 

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I understand aftermarket headers can be purchased to make the GT40P setup work, but will stock 5.0 Mustang headers, not aftermarket, do the job? (can't aford both GT40P setup and new headers at once)
 

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Well I'll just add my 2 cents about the heads. If your going to consider them, go ahead and factor in a set of GT-40 compatible headers. I run the GT-40P heads and Ford P headers and am very happy with the extra output. However I did try using the stock headers and managed to fry 3 sets of plug wires on 2 cylinders so go ahead and get the right ones and save yourself the headache.
 

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Are the GT40 heads worth the effort and cost.
How much more performance?
Thansk for the info.
jack
 
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