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Decat'ing S3 pro's and con's??

Discussion in 'A3/S3 Forum (8L Chassis)' started by Rob_B, Sep 1, 2010.

  1. Rob_B
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    Rob_B Member

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    hi chaps,
    i was wondering how many people have decat'ed there s3? and what sort of gains you get?, also weighing up the best way of doing it?

    im looking to get a milltek performance exhaust for my s3, was only going to go for a cat back(due to budget)

    so in terms of a cat bypass i was thinking of getting a cheaper one on ebay rather then spend alot more money on a milltek(or alike) one, i did a quick seach and it seems that space is an issue and it may not be the best idea going cheap as it may be a bitch to fit...am i correct??

    that got me on to thinking - it the bore diameter of the stock cats and pipe are large enough - then why not grab a second hand stock cat and pipe and simply gut the internals of the cat and use that??

    let me now your thoughts guys
    #1
  2. Lee172
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    Lee172 GT3071

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    Im in a similar situation at the moment.. Although im going to concentrate on downpipe rather than cat back as i was told that doesnt make any differance to performance.. its just noise.
    #2
  3. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    Not much gain in doing this especially if you leave the OEM downpipe... 3" DP and 200 cell cat is the preferable route... gets actual gains and remain legal... I run a 200 cell on mine and not suffered..

    <tuffty/>
    #3
  4. sportstractor
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    sportstractor Chugger Regional Rep

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    i wouldnt decat, as its too much hassle come MOT time. If you want to fit a sports cat I would also go for downpipe. Been considering fooling with my exhaust as mine does sound very blowy, would probably just go for a miltek catback.
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  5. Rob_B
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    Rob_B Member

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    well i've got my own workshop so changing in not a issue at all...so guessing the downpipe is the thing to change - however are there any gains at all with a decat and exhaust?
    #5
  6. brys3
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    brys3 Member

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    I've got a milltek cat back and I bought a ths decat which is excellent quality However trying to find a downpipe to fit the standard duel cat fitment is impossible
    #6
  7. S3KO4
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    S3KO4 Member

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    Milltek cat back showed 8 bhp gain and 14 ft/lb torque, but if you look at Welly's email to xs-power you will see his DP and decat helped even more. I would choose decat over sport cat, as it is still resticted. keep the sport cat for MOT times :)
    #7
  8. Welly
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    Welly VX220 SC Driver :)

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    Second this - downpipe and decat have really made a massive difference over the OEM item. Again, I was running high boost (22 PSI), so the heat has dropped from the less restriction in the exhaust, as well as improving overall flow....

    Looking at an exhaust manifold now....
    #8
  9. S3 Paul
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    S3 Paul Moderator Moderator

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    Taking the Cats out will get you on first name terms with the VOSA man...
    Bad times
    #9
  10. Rob_B
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    Rob_B Member

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    nice one, how much you gonna charge me for your stock cats so i can gut them?? ;)
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  11. Rob_B
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    Rob_B Member

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  12. Welly
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    Welly VX220 SC Driver :)

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    #12
  13. Rob_B
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    Rob_B Member

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    yep just read through you xs power thread...so im guessing thats the one to go for?
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  14. Welly
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    Welly VX220 SC Driver :)

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    I sent the pipe back to them yesterday, and they have confirmed receipt of that today.

    They are sending it to their suppliers to have the necessary changes made to the item.

    Hopefully they will keep me informed of developments. Jason, the guy I have been in touch with always replied to emails so I am hopeful this will be the case.

    Wait until they have renewed stock of the correct flanged item, and then buy one.
    #14
  15. Rob_B
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    Rob_B Member

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    excellent, im guessing it will marry up fine to a oem system? as if you get most gains from the downpipe and decat i will do that first and wait to buy the miltek cat back when i have the funds
    #15
  16. Welly
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    Welly VX220 SC Driver :)

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    Should do indeed. The decat pipe drops down to 2.5" to marry with the OEM system.

    You may need a small sleeve to lengthen the decat pipe. I have advised them that it's a bit short, so hopefully this won't be the case.
    #16
  17. Rob_B
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    Rob_B Member

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    top banana!! i will keep an eye on your thread mate...as soon as i see the all clear i will be purchasing it :)
    #17

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