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  1. #1
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    a few decat pre-purchase questions .........

    hi all, i am looking to buy a decat for my 2000 210bhp S3 and had a couple of questions.

    firstly, would the same decat pipe fit all S3's built between 99-03 no matter what engine is fitted?

    also, will i have engine management issues? my car already has an air filter, backbox and re-map fitted.

    any help much appriciated!!!

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  3. #2
    superkarl's Avatar
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    Yes, all the same turbo therefore all the same downpipe.

    You may, and most likely, will have an engine management light on with a decat, because your post cat lambda sensor will be reading that the cats are ****ed (because there isnt one). It can be mapped out tho, and there are spacers so that the sensor is out of gas flow slightly, which according to some people doesn't bring the light up.

    May I ask which dp your going for?

  4. #3
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    ok cool, i havn't decided which decat yet, was just looking for a basic decat really. nothing too expensive like a sports cat, moneys a bit tight lol. will it run/idle rough with a decat if the engine management light comes on? i presume it will put the fuelling out?

  5. #4
    superkarl's Avatar
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    No wont affect fuelling, pre cat lambda controls that, if you have one, I think.
    Oh so just a decat on its own. If im honest there isn't much if any benefit from that, your downpipe and decat will still be two small pipes before it goes into one.

  6. #5
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    i thought if there wasnt a cat in the exhaust then there would be less exhaust gas restriction, and so make a better air flow through the engine and so improving performance?

  7. #6
    Andrew@A.L.D's Avatar
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    It will affect the fueling as the gasses are passing the lambda faster not getting a proper reading as its when the the cat is fitted the gasses are slowing down trying to pass though the cat
    Was 531bhp 8L S3 thats going to break the 600+ bhp Club then break something else. Lets see what this OD HTAGT3582r can do
    My S3 Twists Drive shafts for fun.

    FOR SALE
    Sparco Torino 2 sport seats
    Adjustable FPR from 1-5 bar, 2 sets of Unused ARP 3/8 2000 rod bolts
    , relentless 200 cell cat pipe, Std AGU Crankshaft. Ported & Reconditioned Cylinder head service.

  8. #7
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    so basically, is a decat a waste of time with the mods i already have? or will it improve performance? will i need to do anything more once the decat is fitted or will the engine management sort itself out?

  9. #8
    A3tell's Avatar
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    to get the most flow gains, you would need a bigger dp with the decat! the dp is the more restrictive part!

  10. #9
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    i would have thought the cat was more restrictive than the downpipe as its full of baffles.....

 

 

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