renault scenic 1.9 dci black smoke no loss of power ?

the car has a new turbo and has just had a new vacuum pump fitted. intercooler and pipes where cleaned and new oil pipes and gaskets where fitted. car smokes abit when normal driving then turns black and is abit now when you put your foot down. been advised it might be a blocked exhaust/cat or from inlet side. how do i find out which one is the problem. could it be to do with the egr valve