I think the passing power comments are from the anti-diesel crowd.
I'm always surprised how fast it ends up running if I pull out to pass and don't ease off on the throttle...and it doesn't need to be turning 4000 to make that happen.
L3B Engine, TurboMax, (310 hp [231 kW] @ 5600 rpm, 430 lb-ft of torque [583 Nm] @ 3000 rpm))
L84 Engine, 5.3L EcoTec3 V8, (355 hp [265 kW] @ 5600 rpm, 383 lb-ft of torque [518 Nm] @ 4100 rpm)
L87 Engine, 6.2L EcoTec3 V8, (420 hp [313 kW] @ 5600 rpm, 460 lb-ft of torque [624 Nm] @ 4100 rpm)
LZ0 Engine, Duramax 3.0L Turbo-Diesel I6, (305 hp [227 kW] @ 3750 rpm, 495 lb-ft of torque [671 Nm] @ 2750 rpm)
It's the torque that hits you in the back when accelerating -- LZO