Custom exhaust, what cats?

[John.]

Anyone have any experiences of replacement catalytic convertors?
Looking into a custom made exhaust and looking to have the cats replaced too.
I'm thinking 2x400 cell cats?.....not sure what that would compare to the originals that are fitted at the moment?
Haven't spoken with the fabricator yet but they've been in the business for a good few years now......do I go with their advice?
Engine is ABY. Internals are standard but ECU is chipped, circa 280 HP

Thanks.

[Greg_S]

A single CAT should be fine, the only reason for two I can see is if clearance is an issue.

[John.]

A single CAT should be fine, the only reason for two I can see is if clearance is an issue.

It's got 2 at the moment, was thinking the exhaust place would position them where Audi put them?
Will see what they say, my main concern was that they (the cats) do what they do sufficiently to meet MOT regs.

[K Simmonds]

It kinda depends if your leaving the down pipe stock then it would it make sense to use two, if going for a custom down pipe I'd use one... A nice new modern sports Cat (something like a Magnaflow) will be more efficient than the current one's that are knocking on for 30 years so as long as they know what they're doing and fit one's the correct size you'll have nothing to worry about.

My old 3B use to pass the emissions test with no Cat at all, though I know they've changed the MOT rules fairly recently so that might not be the case now.

[Waje]

I have a 3" magnaflow cat in a 2.75" line and it passes gases without a problem, when I did the complete line I chose to change the 2 for 1.

CHEERS