Thanks for the reply and info.
My mechanic, who happens to be a btcc mechanic as well, test drive the car when he changed the prop shaft coupling and says with the remap it seems as though they have wound the boost up pretty high. So the turbo could be a good shout, the white smoke is only on start up or idle for a few minutes and then there is none, even under heavy acceleration! It feels very quick all through the rev range so I am pretty sure I am not getting any loss of power, may not be related but worth mentioning that at idle the car feels lumpy but the engine sounds smooth although you can feel the car shaking a bit like something that turns is out of balance??
Also the previous owner had the dmf changed to a solid flywheel when he put in a new clutch. Can't guarantee how well this was done as they didn't even bother to change the release bearing!!