Found this SVA emissions info, appears that if you can prove your engine was made between Aug 1986 and Jul 1995, the emissions required to pass are the same, still not sure where or what the CAT test involves though

This has me a little puzzeld too. According to tigers site a cat is need on post 95 zetecs, so how come its needed on post 93 cars?

I think the reason is in the wording of the test document. It says that engines fitted to cars between 92-95 which are not listed in the tester emissions list are allowed the non cat emissions. I have never seen any kits listed in the book so they are tested on the non cat spec. Stick to the letter of the document and no cat required!

That make sense, as a 1994 Nissan 200sx doesn't need a cat as it not in the book.