Luckily police don’t have enough time on their hands to search through car forums to find cars which have had the DPF, CAT modified or removed. They would have a field day as most people who join the forums especially previous ones I’ve being on are interested in modifying a car and increasing the bhp/performance. And the best way is too remove the restrictions hence people removing CAT’s/DPF’s. I’m sure one day they will bring in more road side & random strict checks to catch people out but currently as long as the car has passed its MOT then there’s not a lot they will do. Luckily people always know someone who will turn a blind eye at MOT time or go the extreme of refitting the CAT just for the MOT. I’m sure things will change rather soon with the whole anti diesel campaign but people will always come up with other alternatives