That said though, Aragorn. The tuning box i used to have on my tdi avant was a bit more intelligent, it used a MAF input to fuel only when there was enough air to go with it (ie under boost).
Symun, Turning the dial down a couple of notches should, in theory, stop the excessive smoking. But as aragorn has said, diesels inherently smoke (especially when under hard load), and adding more fuel will make more smoke...