2.5 inch exhaust vs 3 inch

Discussion in '96-04 - 2V Specific' started by mtang98 gt, Feb 15, 2015.

  1. mtang98 gt

    mtang98 gt Member

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    Hey guys my current set up is leaving me wondering if its time to up the exhaust from 2.5 inch out the back to 3 inch. I currently have a hand ported pi intake manifold, cnc ported heads with fairly large cams, bbk shorty headers running into a offroad xpipe glasspacks and flowmaster tailpipes. Any help is appreciated thanks!
     
  2. Caboose302

    Caboose302 Well-Known Member

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    I don't really think a 3" in "needed" until your boosted or pushing a lot of hp. My old Camaro had 360 hp and had that goofy 3" single exhaust and breathed just fine. In some cases I would think the loss of back pressure would cost hp.
     
  3. the5.ohh

    the5.ohh Legend

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    3" would be overkill. Stick to 2.5"
     
  4. mtang98 gt

    mtang98 gt Member

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    seems that the general consensus is to keep running 2.5 thanks for the help! now to find a nice set of mac longtubes
     
  5. 96blak54

    96blak54 Legend

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    Actually. ..2.25 duals is way plenty
     
  6. Caboose302

    Caboose302 Well-Known Member

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    Other than stock, where would he find 2.25 exhaust? I think if you're talking about a bolt on car then I don't think you get much difference, but once you start talking about ported heads, intakes and cams, the mandrel bent 2.5 is going to help it breath better.
     
  7. 96blak54

    96blak54 Legend

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    Exactly. ..if all you can budget is swapping out the stock cat H-pipe for a 2.5 aftermarket catless ...thats the major improvement. Ditching the cats is were its at!
     
  8. 97stanger

    97stanger Legend

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    You are definitely not in the range for needing 3" exhaust. I've seen it become a restriction in the 700rwhp range before on a buddy's car, but unless you are running crazy boost I would just stick with 2.5"