I considered that one

Anyway, 3.0 Cats can be fitted to a 3.2 (it has been done to one of Jimbob's cars) and they are believed to be slightly better flowing. You need to modify the flange where it meets the manifold and fit the extra Lambda sensors in too
(you may need to extend the wiring)
As for the MOT... It gets tested on the fuel it is presented (make sure you inform the tester it is running on LPG if that is the case) 
Oh, and removing the cats would now be a failure as they must be fitted
But you could smash the insides out and then refit the straight pipes

Haha!
It's not the best plod car.... rusty, may need brake pipes, sills are rusty under plastic skirt, but want to mot and use for 4 months, try gas out then break plod car, remove gas to a 3.0 estate, happy days, oh lsd too

The problem with auto box was a garage fitted a seal to box and removed to fit, as ATF so then needing topping up i think looking at it they used black old used engine oil

didn't smell of ATF at all, flushed all rad and pipes, fitted another AR35 and result, drifts very well

Very powerful plod car
