[Vwdiesel] Up my boost?

[DAN SNYDER]

Under part throttle operation, a diesel (turbo or N/A) runs lean, meaning some oxygen exits the engine "unused". As you press down on the throttle, more fuel is injected and the mixture gets less lean. At some point, all the oxygen is used, and beyond that point, you just get soot out the exhaust, but no more power. 

The only time that more turbo boost would do any good is the beyond the point where all of the oxygen would be used if you didn't have the extra boost. The rest of the time, you would just be wasting energy compressing more air than you needed to. 

Dan