Amy time you lugg a diesel down its adding fuel to tey and compensate for the heavy load, thus the black smoke. Black smoke is partially burnt fuel. Adding the turbo increases the airflow allowing more available air during the same time the govenor is adding extra fuel to try and maintain rpm at a given load. Therefore just adding the turbo will increase power. Adjusting the full fuel screw will gain more power to the point the turbo can't flow enough air to compensate. Advancing the timing will also help lower egt, but increase peak combustion pressure. It's always a give and take.