ideally I would run the 8374 on the surge line till the max boost you octane/AI can support till you reach lets say 450 whp and then taper off boost so hp remain constant and torque drop.

I always try to tune diesel with VNT turbos this way. you get a plateau of power instead of torque so once you are on the power plateau (often reached at 2/3 of redline rpm) it lets the need of a downshift disapear. it is a killer on the street and track as while other cars (especially NA) need to shift 2 gear back you can just floor at 4000 rpm and be in the blink of an eye at 400+ hp.