So, where anyone has had a cat/ DPF removal and delete (because lets face it, no-one has an aftermarket one fitted), your cars will now fail the MOT
For anyone still considering this course of action an alternative would be to remove the internals so it still looks like you have them fitted as there are no plans (at the moment) to reduce the levels of measured smoke, or better still if you're concerned about gas flow, ensure that your straight through pipe runs through the original casing
My biggest concern is that this may be a prequel to a significant change in the measurement of particle matter, then god help us all, even standard motors