GolfGTIforum.co.uk
Model specific boards => Golf mk3 => Topic started by: Rideandy on 17 February 2007, 17:28
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Hello
I have been thinking about decatting for a while now, can anyone tell me if there is any down sides to doing this, my insurance company will only up my excess which surprised me.
I have seen a brand new one on ebay which I thought I would go for, but thought best to ask you lot 1st
Cheers
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i also wanted the answer to this but i got moaned at because of it breaking the law,if you want to do it cheap break all the insides of the cat out and then it is decated :shocked:thats what some have done but still dont no what it does for performance.
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Breaking the law yes, but the insurances groups still allow for it?
I wonder how you stand if the old bill pull you over and notice!
Cheers
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A decat gives approx 5 - 10bhp depending on the rest of the exhaust bore etc, btw it is NOT illegal to remove the cat or drive without one. Its only a legal requirement for the MOT and even then its only for the emmisions test. If your car has a decat but passed the emissions test they wont fail it either. If it is MOT'd with the cat fitted and then the cat is swapped for a decat pipe its perfectly legal too.
I had a decat on my scooby but only one of the cats was replaced as it had 2 and one is hard to get a decat pipe for, so I only did the easy one. It passed its MOT no prob as the co level was low enough. A computer analyser does the test and it cant see the cat, just the CO content of the fumes! The MOT tester guy said it doesn't matter as long as the test is a pass.
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I am not a big believer in de-cating normally aspirated car's...I have had a few decated and only ever saw 2-3bhp and that was up in the rev's and I all way's thought the car's felt slower lower down.
I was all way's led to believe that for more power on a n/a car's you need more commpression and as far as i know the exhaust/cat help the engine to do that and on turbo car's once the exhaust gas has gone through the turbo (which when boosting increases compression) the gas dosen't do anything else with the compression and that's why decatting a turbo gives good result's
Don't know if any one will understand that but I am sure that's how it was explained to me (all them years ago!!!)
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i always thought the way boney is describing is the way a supercharger worked whereas a turbo just slammed more air in rather than being involved with the exhaust gases, any clarification would be welcome, sorry if im being a bit of a hyjacker!
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Cheers chaps.
So it's looking like a no then! I really thought this would be a bit of a power boost!
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De - Catting the car should make a difference, in my experience a NA car still gets some benefit, although not necessarily all out bhp but in the responsiveness of the revs and driveability of the car.
The cat is there to help reduce emissions. If your car was first registered 1993 or after (unless an it's an import without a uk equivalent like an MR2 Turbo) they will do a "cat test" at the station. This is a lower emissions standard than the earlier cars. If your car is tuned well it can pass without the cat however, the cat sensor (lambda) is a part of the self measuring process in the car, it feeds info to the ecu. I'm not sure if there is a decat with a hole for this sensor about.....
The old bill won't know whats going on if you car is not blowing blue smoke but the random VOSA checks which are often set up these days will because they will test it and impound it at the roadside if it fails.
So it's up to you, but every time I think about it, I can't be arsed. :cool:
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Thanks for the feed back.
Still not sure, there is a decat pipe on ebay that I was (still am) looking at.
No one here has one fitted!
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Dont know about legality but I guess its because it invalidates the MOT.
If a car is fitted with a CAT as standard and some cars were fitted with them before they became a requirement! then it must be fitted and working properly at the MOT.
Automatic fail if not!
So yes you can take it off and run the risk of getting caught, BUT you must refit it for the next MOT.
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I am not that worried about the mot side of thing as i have found a place that will over look that part of the mot :wink:
still unsure though
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I dont see how they can as it wont pass on emmissions!
So what else will these cowboys overlook?
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Its the old - stick the measuring thing in the car in the next bay trick. Used by cowboys everywhere! :undecided:
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See that worries me. I mean there are enough bad drivers out there without having dangerous cars as well.
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No these blokes are not cowboys. yes they are bending the law a bit ,but an mot means F all after you drive out of the garage!
My bird takes her Vantage there all the time!
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I will add my 10p worth now...... my old car (1995) had a decat fitted and passed the m.o.t as the emmision's were still low enough.
Regarding them being cowboy's... If your gas man said your boiler was putting out carbon dioxide would you let him bypass this test by going round your neighbour's house and testing there's to get a pass???
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Like the analogy!
But I always thought if a car was supposed to have something fitted as standard then it being missing or not working was an automatic failure, like ABS.
Rideandy - if your bird drives a Vantage why do you have a Golf?
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Gasman ? Carbon dioxide ? Like what plants give off!
Len you saying your car is all standard? Don't think so!
I drive a Golf because thats what I want to drive !
All I am saying is that I was told that it improves the performance and have asked if anyone has fitted one, as it does seem like a cheap mod for improving the bhp
As said, the people I use are not cowboy!
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my old vr and gti were de catted and tbh i would,its a pain in the arse to do,but once you got the new bolts holding it together you can take it off at m.o.t time then back on after!! :laugh: :laugh: :wink: worth doing in my opinon! :wink:
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I wasnt telling you not to do it mate and yes it is a cheap and good mod.
My concern was that if any MOT station did illegal things like you say they will, what else will they let slide?
If I did it I would swap back at MOT time thats all.
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Slim-dub, thanks for that,I think now I will defo get it done.
Len, point taken mate, I have asked around about fitting and I am being told around £10-£20, so I think I will go down the route of mot fit after then take off and fit cat, will give a year without cat and see if worth decatting again after mot.
Oh and my bird drives a Vitara :embarassed:
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Vitara!? :laugh: :laugh: :laugh: Someone has to!
let us know if it is worth doing mate! :wink:
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Will do.