Mine failed the emissions test on the MOT last year, but passed the retest. So I'm guessing the tester did something similar. Whether or not that is because the OEM cats are knackered and need replacing I don't know.
Hmm, after a bit of research it looks like a decat would need a remap. lol so thats about 700-800 for decat and full exhaust then maybe 400-500 for a remap... lol pretty expensive