there is an advantage to smoke, but not ridiculously black smoke, that is just for show..
but remember excess fueling will cause high egt's but this is due to the fact that the combustion event is still taking place after the exhaust valves have opened and is still burning in the exhaust manifold...
as these gasses are still rapidly expanding due to the combustion process it spools the turbo faster because the exhaust has more velocity and energy heading toward the turbine...
so for the sake of performance, some black smoke is necessary...
given two identically equipped trucks, the one making the smoke is going to be the quicker truck because it can get up on boost faster...