I used to have an Audi A3 tdi and I had the dpf removed and the car was remapped.

It passed the emissions at mot time with no problems.

Not only could you barely see the filter as it's tucked up the back of the engine but it was gutted from the original system so visually you couldn't even tell it'd been opened and removed internally.

You would of needed to remove the system to check if it had even be tampered with to prove it had been removed which let's be honest wouldnt happen.

If it's a clean roadworthy car that passes it emissions and you can't tell it's been tampered with then no one would ever know.

It also says in that article your insurance 'could' be void, not will be void.
Like many other menial rules and regulations imo it actually doesn't make much difference.

You could even just claim you know nothing about it being removed.

Cheers Paul