No contributions, what does it take to get debate going on here? I'll attempt to kick it off then
Of course the Mk2 Focus 1.6 TDCi has a Cat come DPF combined. So taking both of those two exhaust cleaning processes out of the equation, would I suspect possibly result in a MOT emissions failure. Maybe, maybe not, but as I don't have any expertise in that area, honestly don't have a clue. Then again maybe the company offering the service would be able to give any body interested in possibly having it done, the heads up in that regard........I bet hawker would have been interested in having a definitive answer to that question.
Even if it is possible to do the Focus 1.6 TDCi Cat/DPF, or in the case of the Focus 2.0 TDCi which is a stand alone DPF. How do you go on at resale time when you come to PX it? Even selling private, if your selling to a DPF ignorant punter, they would not realise the diesel economy and maintenance savings, not having one could bring. But just think Oh er, it's been tampered with, best give it a wide birth.
And if the DVLA were to find out you had had it altered, how would you stand legally?