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Discussion Starter · #1 · (Edited)
READ EDIT FIRST

Okay, so by now, everyone is aware that headers for the v6 do little in terms of performance, and its not even really the headers that cause this, but its because you are removing the stock restrictive pre-cats and cats.

Question being, if headers aren't really an option, would you get almost identical gains by throwing on test pipes in place of the stock pre-cats? (My car has already had the main cat removed) and how much would my car really benefit from that mod? My current mods involving airflow are CAI, GTS intake manifold with working butterflies, 3rd cat removed, and custom 2.75" (I know, overkill) catback exhaust (starts where the 3rd cat would have been after the Y joint) and a tune by TxCodeman.

Any input is appreciated.

Thanks.

Edit: Ignore this thread/question, unless you really feel your input helpful, as I have decided to just keep things the way they are for whenever I get something that I can actually make fast.
 

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Stage 1 SDS @11+ psi
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Sure the stock exhaust system is a bit restrictive. But you're not going to see high gains from your test pipe or headers unless you tune it out properly using the ECUFlash. And to be perfectly honest, the gains you get you won't really 'feel.' It's the 74/75 swaps and FI that are the real deal.

I'm not sure the GTS manifold with working butterflies is worth it. Just get the larger plenum intake and you'll be fine.
 

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Discussion Starter · #3 ·
That was what I did. The GTS plenum is much bigger than the stock GT plenum. I could have went for even bigger but that required additional throttle body/mods that I didn't feel was worth it. I already have the GTS plenum, exhaust, and tune with ECU flash for current mods and everything.

Although it was nothing I could definitely feel, i think the plenum was worth it when comparing the potential of that plenum vs the stock GT garbage plenum. Plus the sound difference and the little extra pull you feel when the butterflies open is worth it itself, at least for me. The only airflow mod/big 3 mods (I/H/E) that hasn't been done to this car is headers, and like I said, its know that really the only gains are from removing the stock restrictive cats. It was just a question that I happened to think of randomly. I cant even find a bolt on test pipe for our car anyway, and I don't know anyone who welds for cheap anyway so the stock manifolds and pre-cat will most likely stay.
 

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Stage 1 SDS @11+ psi
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Oh, I misread your post. You already got the working GTS plenum....

Any horsepower gains you will get up will be top, you will lose a little low-end torque. That's what I documented when I got headers installed.
 
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