is it worth taking the cat off?

[Dave_GTI16v]

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?

[Burnsy]

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

[jte]

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.

[golfvr6]

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.