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3.2 decat

Discussion in 'A3/S3/Sportback (8P Chassis)' started by marknjayne, Mar 16, 2012.

  1. marknjayne
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    marknjayne Member

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    [Mar 16, 2012]
    going to be making up a decat for the 3.2 A3 on thursday,being built with shark performance,looked at the r32 owners forums and find that decatting gains around 15hp (they have run before and after dyno runs),not actually having a full decat as in the whole length ,all we are doing is cutting both cats out and using two 2" 460mm decats in stainless flanged to allow the cats to be put back if needed,also the cats will have flanges welded on for the same reason,will give more info on it on thursday when i pick the car up
    #1
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  3. RedDejavu
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    RedDejavu Well-Known Member

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    [Mar 16, 2012]
    how are you going to pass MOT with this mod?:sorry:
    #2
  4. marknjayne
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    marknjayne Member

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    [Mar 16, 2012]
    im not,its for track use,if it works well enough though i may have some 100 cell cats made up,will need a better flowing exhaust ready for the supercharger anyway
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  5. marknjayne
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    marknjayne Member

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    [Mar 20, 2012]
    decats arrived,car now at shark having the necessary cuts and fitting

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    #4
  6. marknjayne
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    marknjayne Member

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    [Mar 23, 2012]
    fitted now,needs the lambdas to be fitted as i need to get some lambda bosses and have them welded in so the engine light is on due to the lambdas being temporarily disconnected and the car is running a tad rich ,again due to the lambdas not being connected,the noise is the exact same as before on tickover and only very very slightly louder under gentle load but as soon as you floor it from low revs (1.5k or so) you notice much more noise,more like an M3 rasp and more torque (never had a dyno run as to be honest they mean nothing,IMO its how the car goes and feels that is important,the dyno to me is only useful for data reading such as air fuel ratios etc),up above 5k you feel the overfuelling im 99.9% sure this is due to the lambdas not being connected,will update when they are fitted

    may look into having a switchable map installed so it can be run with or without cats

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    #5
  7. devonmikeyboy
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    devonmikeyboy As far from JBS as possible !

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    [Mar 24, 2012]
    Just replace the cat`s at MOT time then remove straight after.
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  8. paddy
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    paddy Audi=No fault code, no idea

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    [Mar 24, 2012]
    A before/ after dyno is hardly a waste of time because you will want to know if the decat actually did what its supposed to do or if its wishful thinking. TBH you are not really going to notice 15bhp on the road given that its less than 5% and then only right at the top where a cat might have restricted it. I did countless dyno runs on my 3.2 and there is defo a restriction somewhere be it inlet or outlet. We found we could get it up to 250bhp and not a single bhp more whatever we did. Even remapping !! something reaches its limit. for example we got 10bhp more with Tesco 99, it went from 240 to 250 bhp. We then remapped it and ran Tesco 95 and it ran 250 still with remap but add Tesco 99 again and it still stopped dead at 250bhp.
    #7
  9. discostu49
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    discostu49 Active Member

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    [Jun 11, 2014]
    thread revival

    any videos of the decat on the 3.2?
    #8

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