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De-Cat

Discussion in 'A3/S3 Forum (8L Chassis)' started by big_mo, Feb 3, 2010.

  1. big_mo
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    big_mo MOSES

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    [Feb 3, 2010]
    Need some help before my money bruns a hole in my pocket.
    Have a 2001 1.8t AUM (150) also with a stage 1 cc remap and i want to take the CAT out. All i want to know is.........
    1 is it werth it?
    2 I have a CAT back system by taking that out will it make it any louder?
    3 will it bring any fault codes up?
    4 How meany Lamba probes do i have?
    #1
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  3. Lemon S3
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    Lemon S3 Alex

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    [Feb 3, 2010]
    The cat is pretty restrictive as well as the downpipe so by removing it you allow the gases to flow better. It will be louder, it might bring fault codes up, you can get remaps to take the lambda sensor out but you've already had one done. I'm pretty sure you only have one sensor.
    I'm going to get mine decatted when I get my turbo back system done but have it so I can bolt the cat back in for MOT time.
    #2
  4. big_mo
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    big_mo MOSES

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    [Feb 3, 2010]
    Ok so because i have a remap already will i have to goand get it done again?
    So if i do have the one than it would be before the CAT then it should be good....
    Yeah thats what im going to do just in case Mr MOT man fails me
    #3
  5. DionBullock
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    DionBullock Dion

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    [Feb 3, 2010]
    ive just de-catted mine, (aum 150) with a full stainless system,
    it is pretty loud, and the lovely little popps you get now and again when changing down a gear are quite entertaining (whether theyre doing any damage to the engine im not sure?)

    to get the most out of it, ur better off going for a custom stage 2 map, i think CC do a deal if u already have stage 1 map im sure??

    Stage 2 map is next on my list :)
    #4
  6. 1animal1
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    1animal1 The Clar!! it mouves!!! VCDS Map User

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    [Feb 3, 2010]
    i was under the impression the S3/A3 CAT's weren't that restrictive..... it isnt a common mod for that very reason.....
    #5
  7. S3 Rav
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    S3 Rav Well-Known Member

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    [Feb 3, 2010]
    I thought the cats weren't that restrictive. Results are in the stickies I think.
    #6
  8. K6V SM
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    K6V SM New Member

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    [Feb 3, 2010]
    well am lookin for a cat back exhaust and maybe a dwn pipe, should i bother with thede cat then???
    #7
  9. DionBullock
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    DionBullock Dion

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    [Feb 3, 2010]
    ive felt the diffrence between having my A3 aum 150 catted & de-catted,

    its not the noise making it sound faster either, i have my own little "test route" (dont laugh!) and compare the before and afters of what ive done to the audi,

    im not claiming or saying it gives it alot more bhp or torque because i havnt had the chance to do a RR printout, but from experience, its made a diffrence to my AUM audi 150bhp
    #8
  10. voorhees
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    voorhees Moderator Staff Member Moderator

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  11. K6V SM
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    K6V SM New Member

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    [Feb 3, 2010]
    forgot to mention i have an s3 210 bhp wi a remap!! am guessin the down pipe makes a diff though, a just want a bit more noise, cars way to quiet fur me
    #10
  12. DionBullock
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    DionBullock Dion

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    [Feb 3, 2010]
    hmm... mine only had the 1 cat to begin with....
    #11
  13. Prawn
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    Prawn My other car is a MINI!!!!

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    [Feb 3, 2010]
    you have two lambda sensors. 1 pre cat and 1 post cat.

    If you remove the cat, you WILL get an engine management light, as it'll think the cat has failled.

    SOME companies can map out the post cat lambda, but most can't/dont.

    The standard cat is not a huge restriction at all, but the standard downpipe on the A3 is a MASSIVE restriction. Ditch it and you'll gain loads of spool up, and more top end as well.
    #12
  14. big_mo
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    big_mo MOSES

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    [Feb 3, 2010]
    Well like i said only got an A3 so i have a single CAT
    Prawn i can have a downpipe made up so shall i leave the cat in and just get the down pipe made up?
    #13

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