I've had a intermittent rattle diagnosed as coming from the cat on my Octy 4x4.

Also been quoted £800 + VAT + fitting to replace it. Mind you it hasn't failed yet and the MoT isn't due till October.

Are 4x4 Cats really this much? My local garage has said if it came to it they could weld a non-standard cat into the exhaust but presumably this would upset the ECU?

Non standard CAT shouldn't upset the ECU providing its suitable, a lot of pattern ones are just to small to work.

Non standard CAT shouldn't upset the ECU providing its suitable, a lot of pattern ones are just to small to work.

Thanks - hopefully it won't come to that but doesn't hurt to check it out