trick97 Posted December 21, 2006 Report Share Posted December 21, 2006 I have recently read that it is currently legal to remove a cat and replace with a decat pipe to any catalysed car first registered before 1 August 1992. Can anyone clarify this? Also, does anyone know what lambda sensors the A3 TDi Sport(51 reg) has - are they before and after cat or just before? Quote Link to comment Share on other sites More sharing options...
Tunbridge Posted December 21, 2006 Report Share Posted December 21, 2006 Yes I believe this is correct. I used to run my 95 Mini Cooper 1.3i with a decat pipe and just used to put it back on for the MOT. Obviously I was running the risk of getting done by the Police in road side checks etc but the chances are slim. And with a 1991 registered car you will be fine. BTW the performance difference it made was surprisingly significant but that was on a relatively straight forward engine with very little in the way of electronics and sensors. Should be OK on your 205 I would think. Does anyone know what would happen if you de-cat an S3, does it go like stink or run like a bag of spanners? Quote Link to comment Share on other sites More sharing options...
Paul Posted December 21, 2006 Report Share Posted December 21, 2006 I always thought it fell upto about J reg, so that sounds about right. I wouldnt waste your time decatting an S3. A. Illegal. £1000 fine iirc if caught.Unlikely, but you need to know the penalty. I will admit however, ive only ever seen 1 roadside check in 10 years driving. B. A few have done it, and i dont know of anyone thats kept it. (their reasons unknown) C. Dependant on year, early S3's have one lamda before the cat. Later ones have before and after cat lamda sensors. the former easier to decat without ecu faults. the latter, less so. The ecu expects to see an improvement in the emmisions, comparing the two readings. If it doesnt, it will flag a fault and shut the car down into limp home mode. D. Sports cats do largely sod all on the S3, so the cats are not the restriction. Its well known the S3 exhaust is good. Its the ports on the mainfold thats the restriction. Quote Link to comment Share on other sites More sharing options...
Tunbridge Posted December 21, 2006 Report Share Posted December 21, 2006 Cheers for that Paul, I did once get stopped for a roadside emissions check but it was about 7 years ago and I suspect I was only targeted as I had an old car (1989 Vauxhall Nova 1.0). Luckily my transport has improved a bit in that time! Anyway the car wasn’t fully up to temperature so they just let me go. Plus from what I’ve read the ONLY sensible way of improving performance is to get it re-mapped. I was just intrested to see if de-cating helped. Quote Link to comment Share on other sites More sharing options...
adigraham Posted December 22, 2006 Report Share Posted December 22, 2006 So would it be worth spending the £70+ (if thats the price) on a decat for Tricks A3 TDI? I have the same car and i was going to ask anyway! Quote Link to comment Share on other sites More sharing options...
Paul Posted December 22, 2006 Report Share Posted December 22, 2006 No idea with the effects on a TDI, but for me, the hassel come MOT time, and potential fines alone makes it a no go. Quote Link to comment Share on other sites More sharing options...
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