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2.5 inch downpipe

Discussion in 'A3/S3/Sportback (8P Chassis)' started by A3 2.0 tdi sport, Dec 17, 2013.

  1. A3 2.0 tdi sport
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    A3 2.0 tdi sport New Member

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    [Dec 17, 2013]
    Hi, I have a 2.5" cobra catback, I'm looking into getting a decat, would I be better off getting a 2.5" downpipe to match the catback or get a 3" one? Also how loud would a 2.5 be compared to a 3" thanks.
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  2. nluk100
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    nluk100 Active Member

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    [Dec 18, 2013]
    Not sure you can get a 2.5" downpipe with sports cat? They are usually 2 3/4" or 3".

    You could try removing your pre-cat if you want to stick to 2.5", but be careful if you go the DPF removal route as it could be an MOT failure from next year

    In terms of noise, it's not so much the bore size but the lack of pre-cat and a less restrictive main cat that makes them louder.
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  3. A3 2.0 tdi sport
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    A3 2.0 tdi sport New Member

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    [Dec 18, 2013]
    Pre cat meaning the middle box? If so that's 2.5" straight through already and there are 2.5 inch downpipes about, currently looking at a miltek one and ppt tuning one both 2.5", I'm mainly doing it to increase power and turbo howl, also as far as I'm aware decats on diesals are legal.
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  4. nluk100
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    nluk100 Active Member

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    [Dec 18, 2013]
    The pre-cat is the first 'block' after the turbo.

    Milltek only offer 2.75" systems for A3 TDI's - I have access to their technical system.

    Also, read this post on DPF removal - things are changing ... http://www.audi-sport.net/vb/showthread.php?t=205170

    HTH
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