iv recently bought an Astra mk3 1700 diesel turbo... and basically, its a great car! it drives perfect, nippy as, and starts on the button, but that aside, its MOT is due on the 17th of next month, and im almost certain it is going to fail, because of its emissions. it is pumping out clouds of black smoke, when you put your foot down when driving along, when stationary and when you hold it at a constant engine speed, its just black soot coming out. its definitely diesel smoke as its just black, no sign of head gasket issues, but i just don't know what to do any more iv changed ALL the filters, oil, ran injector cleaner through it, blasted it 60 miles up the motorway to help blow the crap out of the engine... and all that has helped quite a lot, its not smoking nearly as much, but it is still smoking too much.

Can anyone please help me?!?! im at my wits end with it now :/