De-catting an S3c

[holmbush]

So, now I have bought my S3 and can start enjoying open top motoring when (if)the Summer arrives. One little problem - the cats are quite corroded and starting to blow so I have in mind removing them. I can get by-pass pipes OK but as a newby to the problem, I do not know if the ECU has to be re-programmed or replaced or can it be left to its own devices? Any advice would be welcome as to what are the pros and cons and what additional work is required.

[tvrgit]

Because the lambda sensors are upstream of the cats (ie on the manifolds) the ecu should not require reprogramming / remapping. There might be some slight power benefits if you did, but there should be no disbenefits if you don't!

I took my cats off, no reprogramming, and it's fine.

[dougc]

No re-programming required

Pros
Noise - more of the good sort of noise and less rattling around in the cats.
Engine more eager to rev, particularly at the top end.

Cons
None that I can think of.

Top tip - don't be laying under the car when you take the old ones off, you are likely to get covered in crap.

[Barkychoc]

There is, apparently, some scrap value to cats due to the precious metals in them, so don't just lob them in the bin until you've checked that out.

[holmbush]

Thanks for your advice - the pipes will go on as soon as they are delivered.

[tvrgit]

Barkychoc said:

There is, apparently, some scrap value to cats due to the precious metals in them, so don't just lob them in the bin until you've checked that out.

Mine were completely hollow, there was no metal (precious or otherwise) left in there. I was able to check this carefully after the outer casing also fell to pieces as I took them off.

[jimed]

Decatting is the way - only issue is if your car was regd after 1.8.92 in which case you theoretically still need to have cats fitted but if before then get them off. As mentioned above the engine revs better - and also sounds better too!!
I got my decat pipes from TVR Car Parts but others also sell them so check out the prices.
Jim

[GuyG]

I've got an S3c 1990 and I had my cats bypassed at Dan Taylor TVR, Aylesford in Kent. Dan did a great job for £220 all in. MOT is due soon so hoping it won't give me an emissions problem.