It would appear that ditching the cat wouldn't help me any. If I have a long cat apparently I also have a shorter than normal down pipe, meaning that the standard cat replacement pipe wouldn't fit either.

If do have a long cat then I think I'll have to get the exhaust chopped and the flange welded back on. I don't know what the implications are when I need a new cat though as I don't know if Mazda actually sell the long cat as a spare. The various MX5 parts sites definitely don't sell two different cats.

I know there are other reasons for wanting to ditch the cat, but I'm not that desparate for another 3hp...