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Model specific boards => Golf mk3 => Topic started by: Dave_GTI16v on 31 May 2004, 01:17

Title: is it worth taking the cat off?
Post by: Dave_GTI16v on 31 May 2004, 01:17

i heard u can get more bhp by taking off the cat, but doesnt that fail the mot? has anyone done this? if so, is it effective(how much more bhp) and what did u do about the mot?

Title: Re:is it worth taking the cat off?
Post by: Burnsy on 31 May 2004, 10:17

Im also considring this mod when my exhaust packs up but it will fail the MOT without it on :(
My exhaust supplier (Graham goodes of Leicester) says all you do is just pop the cat back on (4 Bolts he thinks) when you take it in for its MOT.
So ideally get your cat bypass exhaust fitted the afternoon after youve had your MOT ;) so you got a years cat free motoring

Title: Re:is it worth taking the cat off?
Post by: jte on 01 June 2004, 09:32

Any car registered after 1992 (i think) has to have a (working) cat to pass an MOT.

Removing the cat or bypassing it will increase bhp a fair bit.  I think an oxygen sensor (lambda probe?) fits into the exhaust near the cat so you have to make sure this is still in the right place if you remove the cat or your ecu will be very upset.

You should be able to refit a cat to pass an mot fairly easily, but watch out for road side checks etc.

Title: Re:is it worth taking the cat off?
Post by: golfvr6 on 02 June 2004, 00:07

You will need a cat fitted from Aug 92 onwards.
This is when the stricter emissions laws came in, CO must be below 0.5%, you won't be able to do that without a cat.
The bypass pipes that replace cats have a fitting for the oxygen sensor to screw into.