This forum is dedicated to 2014 and newer F series MINIs. You'll have better luck over here
http://www.northamericanmotoring.com/forums/, they have a Gen 1 section and cover all MINIs.
What are you attempting to gain by removing the cat, are you looking for sound or performance, a mix of both? If I remember correctly, on the R53, the pre-cat and catalytic converter are part of the exhaust manifold so you change out the entire unit. I believe there is a way to code out the CEL for the second O2 sensor but don't quote me since I've never done it. Check the link, there are a few threads on De-cats.
Good luck..