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I have a 67 GTO with a Pontiac 455 installed. My mechanic says the engine has a 2 1/4" manifold and the exhaust is currently 2".

I'd like to purchase a 2.5" stainless steel exhaust installed with QTP 2.5" cutouts (key fob operation) and have my mechanic install it for me. If this is installable by someone with limited skills (oil change, etc) then I might look at doing it myself with clamps.

If I buy an exhaust kit from Summit Racing will it fit up to my manifold? Also as I mentioned the manifold is 2 1/4 and the exhaust system would be 2 1/2 so I hope there is some sort of adapter.

Can someone suggest or post some links of exhaust systems which would work? It doesn't have to be from Summit but I'm on the East coast and that makes shipping easier.

Thanks.
 

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I have a 67 GTO with a Pontiac 455 installed. My mechanic says the engine has a 2 1/4" manifold and the exhaust is currently 2".

I'd like to purchase a 2.5" stainless steel exhaust installed with QTP 2.5" cutouts (key fob operation) and have my mechanic install it for me. If this is installable by someone with limited skills (oil change, etc) then I might look at doing it myself with clamps.

If I buy an exhaust kit from Summit Racing will it fit up to my manifold? Also as I mentioned the manifold is 2 1/4 and the exhaust system would be 2 1/2 so I hope there is some sort of adapter.

Can someone suggest or post some links of exhaust systems which would work? It doesn't have to be from Summit but I'm on the East coast and that makes shipping easier.

Thanks.
You're gonna get many opinions on preferences. I have a stainless Pypes system, 3" pro street. It bolts right up like its made for GTO. I have had many over the years even at traffic lights come up to me and ask what I have in there. When the secondaries open up it really roars.

The sound really accentuates my Ram Air IV cam.

Its all in what sound you are after........

https://www.youtube.com/watch?v=RSr7IJFETwo&feature=youtu.be
 

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OP, with stock manifolds the bend coming out of the manifold is very important. Most systems neck down here because they are not mandrel bent which causes a flow restriction. If the pipe is only 2" (or less) at that point it wouldn't matter if the rest of the system is 3" or whatever because it is necked down at that point. The Pypes downpipes are mandrel bent and they have been dyno tested to show gains in that area alone so I would definitely run their setup if I was running manifolds. After that I would say a 2 1/2" mandrel bent exhaust setup and you would be golden.
 
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