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Full Exhaust vs. Dowpipe vs. Axle Back vs. ?

Discussion in 'Engine, Drivetrain, and Exhaust Discussion' started by dgDVM, Sep 28, 2018.

  1. dgDVM

    dgDVM United States Member

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    Has anybody compared the performance gains from upgrading the individual portions of the exhaust? Another way of asking the same question is which portion is the most restrictive?

    Making up numbers here, but:
    I hear one person say they swapped only the downpipe and gained 25 hp, another deletes the muffler and gains 25 hp. I'm sure that a full exhaust doesn't gain you 50 hp, so where's most the gain?

    Ignoring sound for now, will I get any more significant gains from a full exhaust than I will from just the downpipe?
     
  2. brancky3

    brancky3 United States Active Member

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    No. Downpipes are typically the power adders on turbo cars. While full exhausts do make power, downpipes will get you much more.
     
    • Informative Informative x 1
  3. Angeski

    Angeski United States Member

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    So if we upgraded the downpipe to 3in wide instead of factory (2in i think), we talking 25 hp?
     
  4. Adamdan

    Adamdan Canada Active Member

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    I thought I read downpipes gave 30whp. They are the same size as the stock pipes the gains are from deleting the second cat.
     
  5. niko

    niko United States Active Member

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    The ssr downpour gave me 30who and 26trq I have the ssr axle back too which frees up a little more power but I don’t have a dyno on that yet.
     
  6. Doel

    Doel United States Active Member

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    the most gains are from deleting the cat as this is the most restrictive point of the exhaust, but this will make your car "illegal", road legal cars must have a cat. From the dynos I've seen I would probably guess 40-50 hp gains from a turbo back exhaust without cats with stock boost and turbos.

    I used to have a 1.8T GTI with a 50 trim turbo, no cats, no muffler, open wastegate, that sucker was LOUD.
     
  7. Angeski

    Angeski United States Member

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    Will there be any results if i just upgrade the downpipe on my stock exhaust system? Also, if i put HF cat on, will it signal a code on my dash?
     
  8. Adamdan

    Adamdan Canada Active Member

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    Well there is a cat right up at the turbo then the o2 is up there. You could just remove the second cat and it will be just like the downpipes with no cats. I don’t know why they call this part a downpipe it’s more of a mid pipe.
     
  9. STINGER

    STINGER Bahrain Active Member

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    You can run good quality HFC's and stay legal and still make a lot of power.
     
  10. Angeski

    Angeski United States Member

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    ok. I havent got under the car yet so the order for the exhaust is : manifold-turbo-cat-dp-catback exhaust- mufflers?
     
  11. Adamdan

    Adamdan Canada Active Member

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    Manifold turbo cat o2 then secondary cat that can be deleted then cat back. You will get no check engine light from deleting the second cat.
     
  12. dgDVM

    dgDVM United States Member

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    I also haven't been under one yet, but from what I understand:
    manifold/turbo, then a cat mounted basically directly on the turbo with O2 sensor. Most aren't messing with any of this.
    Then, the downpipe with secondary cat. You can swap this out to larger diameter and without a cat for more power and no codes. Most gain is here.
    Lastly, catback "might" get you a little more, depending on how free-flowing the stock system is. I haven't seen any comparisons on downpipe only vs. downpipe+catback. This was my question, how much more will I gain?
     
  13. Angeski

    Angeski United States Member

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    Ok. Thats good to know. So we add the DP by takimg out the second cat? Lol
     
  14. Angeski

    Angeski United States Member

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    Ok. If thats whats foing on, then im deleting the 2n2nd cat with the downpipe. Whatever the dp size is ill just go 1 in more or whatever the shop thinks.lol looking for a good sounds upfront more than the back atm.
     
  15. Adamdan

    Adamdan Canada Active Member

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    There’s no point of going bigger I would just keep it the same size. You might as well just get them to cut out the cat and weld in a pipe... only downside is you cut up the stock exhaust.
     
    • Like Like x 1
  16. Angeski

    Angeski United States Member

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    Talked with an exhust shop. They didnt even feel comfortable in doing anything to it. Jesus. I hear import mike is making downpipes and already made muffler deletes for the 2.0t. Could be something.
     
  17. Jonathan

    Jonathan United States Active Member

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    LAP3 | Product Page

    I believe these just became available. Primary catless downpipes. Apparently the biggest choke point in the whole exhaust system.
    The downpipes that SSR offers should be considered midpipes/secondary cats correct?
     
  18. Angeski

    Angeski United States Member

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    Yea i believe so.. Thats awesome!! Now they need to make the 2.0T version. Crazy how they are charging that much for a little bit of piping.
     
  19. Adamdan

    Adamdan Canada Active Member

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    I think those would throw a check engine light. And I though removing the primary cats caused car to over boost and to go into limp mode.
     
    • Agree Agree x 1
  20. Angeski

    Angeski United States Member

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    Yea, i can see throwing codes for primary replace. If you have an ecu program, you could reset the code and adjust your boost i think.
     
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