Still disagree. Your theory is based on the HUGE ASSUMPTION that the cars were treated/driven equally.
But in at least 99% of the cases a modified car is driven harder and thrashed more often then a std car, so this higher reving, more heat, etc, contributes to the shorter life span. Nothing to do with boost level.
I have seen a few stock rb's go give up the ghost at less than 100k, due to how the car was driven.
Then you got stock engines like Troy's (Roy) with big turbo, injectors, pfc, etc, making 270rwkw, doing track days, motokahanas, drags, etc, that never want to die.