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  1. #1
    Slipping at 3.5Krpm

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    Anyone got Decat?

    Weird title I know, but it'll make it easier to search in future.

    Has anyone here put a decat pipe in their A3/S3?

    I'm specifically interested how they are controlling the lambda sensors now that both will be producing the same readings, and if they needed to be replaced as opposed to using the old ones...
    <Insert meaningless geeky specs here>

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  3. #2
    Ballcrusher's Avatar
    NO CAT JUST 3" STRAIT THREW

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    ive decat mine but ive got an early s3 wer theres only one lamda witch is at the top of the downpipe



  4. #3
    A3_Turbo's Avatar
    Swaying towards IHI....

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    Dave id strongly advise you not to do it.

    I had a full stainless De-cat system at first and past 5K Revs it made a horrible high pitched whistling noise.

    I had it on the rollers at AMD and it was 15bhp down on power too from the De-cat.

    I since then stuck a full miltek system with high flow cat and it was so much better!

    I dont know of any-one else that has De-catted an A3 1.8T but that was just my expierience of the De-cat.

    Jason
    A3 1.8TS
    K03S,Pro Alloy FMIC, Neuspeed TIP, Forge 007P,Jabba Stage 2, BMC CDA, Turbo Back Miltek,H&R Cup Kit,H&R Arb's,18" Cup 3's Wrapped in Parada Spec 2's, Facelifted, 10k Hids, Dewipered, Debadged,S3 Interior, S3 Rear bumper, S4 Front bumper, Brembo's, Momo Team, LCR Splitter.

  5. #4
    Slipping at 3.5Krpm

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    Actually, been speaking to some people and yeah, I probably don't need to, the current standard system has very little restriction.
    <Insert meaningless geeky specs here>

  6. #5
    Ess_Three's Avatar
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    I've tried 100 cell, 200 cell and std cats...no differences in power.
    I've seen Star do a de-cat back to back, again no power gain.

    not worth it...especially as you need to re-fit for the MOT...you just don't get a gain that's provable. The placebo effect will convice those that have had their wallet lightened significantly that there is a gain of course...


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  7. #6
    Prawn's Avatar
    My other car is a MINI!!!!

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    i think its more in the downpipe dave.....

    the A3 cat seems to flow perfectly well enough, its just the downpipe with its huge step thats limiting flow there.....

    thing is, can you run a bigger down pipe and retain the standard cat? or do you have to invest in a silly expensive high flow cat as well?
    -------------------------------------------------------------------------------------------------

    Prawns TFSI Turbo'd 1.8T Track Car

    But I know nothing so ignore me.

  8. #7
    Slipping at 3.5Krpm

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    This is what I'm trying to ascertain. I would prefer to replace downpipe and retain cat.
    <Insert meaningless geeky specs here>

  9. #8
    Prawn's Avatar
    My other car is a MINI!!!!

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    same here.........

    do you know if the milltek high flow down pipes retain the standard cat flange? or if the milltek high flow cat has a different flange, stopping us using the downpipe only with the standard cat......

    very tempted to get one of the ebay &#163;100 downpipe/decat jobbies, and cut up a standard downpipe to get a flange for the cat, and weld it onto the new downpipe.....
    -------------------------------------------------------------------------------------------------

    Prawns TFSI Turbo'd 1.8T Track Car

    But I know nothing so ignore me.

  10. #9
    nick-barnes07's Avatar
    3rd Gear

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    i have a de cat in my s3 , and it felt like it made a difference when i put it on ,

  11. #10
    ADP
    ADP's Avatar
    Neutral

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    I fully decated my impreza, the downpipe made the greatest gains by far, noticeably quicker, the other 2 cats being out were just a bonus. No idea on the S3 but Im sure the pricipal in the downpipe remains,.

    Does the S3 have an up pipe?

  12. #11
    Ballcrusher's Avatar
    NO CAT JUST 3" STRAIT THREW

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    my decat made very little differents in power gains but sounded fantastic as you could here the turbo spin up so much better as for noise very not much louder than with a the standard cat

 

 

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