Ok I have a set of JTR 17/8 headers it says no gaskets needed but I would like to use some any way. My heads are PRC cnc LS6 heads with the oval exhaust port and the JTR flange is round what gaskets do I use the LS1 or the LS6 ?

The stock LS1 manifold gasket worked fine on my FD with JTR 1 7/8 headers.

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I am guessing that you don't have the instructions that came with the headers. The header manufacturer explains that you don't use gaskets on the header flanges due to their design. Use a high temp RTV sealant bead 1/8" in height on each port and bolt the headers on. It will seal perfectly and permanently. I have installed 7 sets of these headers this way with no leaks ever.

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87 FC 02 LS1/T56 439rwhp/408rwtq

SOLD!! On to a new build.

I had my JTR's machined evenly at the flange so then I can use a metal gasket

I used the stock gaskets as well with no leaks.

Same here.

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That works but it's more to clean up when you pull the headers off - none of us can bolt it together one time and leave it, you know that!

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felpro stock replacement gaskets here.

idk about the jtr headers, but stock GM MLS gaskets work awesome on an LS1

Dido, work great, like better than stock.

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Bobby Jasan
www.bobbyjasan.com
95 Nissan Altima SE - 87 Mazda RX-7 FP #60 - 89 Mazda RX-7 LS1 EM #57 - 92 Toyota MR2 ES #60 - 04 Subaru Impreza WRX STi STU #95