you'll be fine using a de-cat as long as your car still passes the emissions test, i work at an mot station and theres nothing that says the car HAS to have a cat. however it obviously needs to pass emissions. again if the 5-0 pull you over and do a roadside emissions test,as long as you pass it won't matter that you don't have a cat. after all the cat just cleans up your emissions and if your car's within limit anyway, they can't do jack 8) just thort id say as decats are cheaper than sports cats haha