i agree with what these guys say about not tuning in 1st and 2nd gear,as it will need seperate maps just for those loads.
BUT,
maybe you could try adjusting your spark plug gaps?
as you increase boost,i dont think your coils can keep up with high voltage,so making the gap smaller(say:0.7-0.8mm) may help.
But it sounds like it wasnt tuned properly.