But replying to myself, it seems far from being a nothing burger. Read round it.
I for one won't morn the passing of the stupid exhausts you hear up and down the high street. Bullet rifle shots types, or 0.9L beat up Corsas with a stupid exhaust. I've always wondered how they get through MOTs. Under the new legislation, if the emissions of said beat up Corsa, or rifle bolt popping Astra don't match, there or there about, the car's original factory emission values, which it most likely won't with the after market exhaust, bingo, it fails.
There's stuff about decoring cats too. Maybe Elgrands may have to get new rear cats from Japan (the legislation seems to make it hard for aftermarket stuff, as the emissions outputs are often different) and then not decor them!! Hopefully not! Also straight through pipes will be laughed at. Those look like they will be failing at the MOT door.
Seems muddy at the moment. The overriding thing is though, the Gov't want yours and other people's high Co2 (and not even high co2, if the car is simply not emitting a similar value (which could be low) which it did when new) cars off the roads, and this looks like yet another way of doing it. All for what though? Is there a shred of evidence that doing all they are doing will make a blind bit of difference.