I personally don't see the point in a sports cat. From what I've been told the emissions are still too high to pass an Mot which in my eyes would be the only benefit of still having a cat in the first place.

As for issues with the rozzers I have heard of people being stopped and tested. But in my town there at least 15 decatted 5pot focus St's and none of them ever seem to be bothered by the police