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Just made my JeepForum account, I was trying to PM a fellow jeeper but it didn’t allow me, so I figured I’d write a post about it. I’m interested in installing the Doug Thorley headers for my WJ with the 4.7 engine, any tips or comments as to installing these myself? If there’s any member here who can point me in the right direction as to acquiring these headers, that would be incredibly helpful.
 

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Have a look at this youtube vid of Martins, it may help you.

Beat me to it....Seems like the last time I looked, those headers were no longer available...
 
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They're not discontinued but Thorley hasn't made a batch in awhile. They would if there was sufficient interest - they want me to buy at least 5 sets in order to start a batch.

Beat me to it....Seems like the last time I looked, those headers were no longer available...
 

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They're not discontinued but Thorley hasn't made a batch in awhile. They would if there was sufficient interest - they want me to buy at least 5 sets in order to start a batch.
Ah... good to know...
 

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What kind of power increase do they provide on an HO with full 3" exhaust?
 

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I understand Thorley is finishing up a batch shortly. Unfortunately no one there told me and now the batch is sold out. So they're all going somewhere - maybe Summit Racing will get some? I'd suggest calling Thorley and speaking with either Shelby or Jennifer. They might know if any of them have been sold to vendors for stock.

Mike Johnson was my sales rep over there for over 15 years and kept me in the loop on production. He left the company a couple years ago and I guess I lost my place in line :(
 

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I understand Thorley is finishing up a batch shortly. Unfortunately no one there told me and now the batch is sold out. So they're all going somewhere - maybe Summit Racing will get some? I'd suggest calling Thorley and speaking with either Shelby or Jennifer. They might know if any of them have been sold to vendors for stock.

Mike Johnson was my sales rep over there for over 15 years and kept me in the loop on production. He left the company a couple years ago and I guess I lost my place in line :(
Thanks man
 

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I understand Thorley is finishing up a batch shortly. Unfortunately no one there told me and now the batch is sold out. So they're all going somewhere - maybe Summit Racing will get some? I'd suggest calling Thorley and speaking with either Shelby or Jennifer. They might know if any of them have been sold to vendors for stock.

Mike Johnson was my sales rep over there for over 15 years and kept me in the loop on production. He left the company a couple years ago and I guess I lost my place in line :(
Btw Kolak, does Doug Thorley make set different sets of heads for the 4.7? A "race only" and a "street legal"? Or does everyone just use the race only set and "get away" with it?
 

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They only make the one set for the 4.7. It deletes the precats so it's not going to be emissions legal in areas that require emissions tests and/or underbody inspections.
 

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Discussion Starter · #16 ·

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Yo, I'm curious what you would spend the grand on instead of or before buying headers. Serious question, I'm here to learn (and also building an 02 HO...)

Thanks man
There just isn't much that you can do to the 4.7. I'm not aware of anyone that makes aftermarket cams or heads for these engines. Kennebell made a supercharger kit for them many years ago, but quickly discontinued them because the stock pistons couldn't take the extra pressure. The piston edges would break above the top ring. If you want something faster than your 4.7HO WJ, buy a different ride. :(
 

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Got it. Not looking for the wagon to be a faster ride, other heads are actually made, not for more power or speed but to solve the dropped seat problems.

Mines the H.O. So I've got decent cams already.

Headers, exhaust, and few other minor things ;), for drivability and updating the power plant is my intent.

Thank you for your input.

Sent from my Pixel 5 using Tapatalk
 

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Yo, I'm curious what you would spend the grand on instead of or before buying headers. Serious question, I'm here to learn (and also building an 02 HO...)

Thanks man
I'd put the $$$ towards gears before headers. You're going to see better results with deeper gearing than the typical engine upgrades.

As always, just my .02 worth.
 
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