M100_DMM wrote:It might have something to do with the law. UK market S2s left the factory with cats because that's what the law required. Prior to, I think, August 1992, cats were elective on new UK market cars with petrol engines, but thereafter they were compulsory.
As I understand it, the lack of a cat on a post 31/07/92 petrol car is against the law and should result in an automatic MOT failure. But I suppose if a car looks like it has a cat and the emissions are within the acceptable range then it should get through an MOT.
I Know this is

, and i have written elsewhere on this issue....
...Cats have never been a requirement in the UK MOT....
...it is all down to emmissions levels - not how they are achieved.
When the law changed, the only reasonable way to ensure that the emmissions were low enough to satisfy the regulations was to use a catalytic converter, so everyone did.
However, if you can find another way (or hope!) that the emission will be low enough, then there is no problem to remove/replace the cat.
Manufacturers will fit them because they 'guarantee' to meet the requirements for their 8-year life - they don't want customers returning with complaints every year at MOT time, and have to spend time fiddling arround to get the numbers low enough.
I have known many people with older cars having to adjust the fuel mixture by tweeking the SU/Webber carbs to get it through the MOT, only to have it running like a dog, and then re-adjust them after the test, to drive home.
