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Exhaust question

mjr901 Feb 21, 2012

  1. mjr901

    mjr901 Guest Gold Supporter Audi S3

    Basically at the end of the day I'm after stage 2 atm for my S3 3 door.

    So I'm trying to get there for as little money as possible!

    is there a de-cat that will go onto the standard system that will enable me to have stage 2?
  2. Sidhu88

    Sidhu88 Active Member

    I don't know for sure what the standard exhaust set up is like (one piece of multiple) but If there are no options the simplest thing for you to do is to have the Cat cut out and a pipe welded in place of it. I'd be careful of where ur lambda sensor is though, if its pre-cat you'll be fine, post-cat and you'll need an O2 cheater or something similar to trick the lambda into thinking your air fuel ratios are correct, or adjust it to read slightly differently (not sure..) I know with the 20VT's you can change the turbo downpipe.

    Realistically though, if your upping boost, you need to derestrict your exhaust system to allow the turbo to flow easily through the system. Removing the cat will help massively, but with turbo applications in particular, bigger will always be better. Keeping the standard system with increased boost levels will just restrict the turbo. Peak boost will probably big mid-range and it may even lose boost in the upper RPM region
  3. Spin140

    Spin140 Well-Known Member

    The downpipe is the most restrictive part of the system, you can get away with mating either a decat or sports cat to the oem system, Warren s3 did this on his previous car with no issues.
    Take a quick look on mk5 Golf Gti forum as there is a decat DP for sale in the classifieds for £100, from a K04 so should be a direct fit.
  4. Spin140

    Spin140 Well-Known Member

    Here you go -http://www.mk5golfgti.co.uk/forum/index.php/topic,42345.0.html

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