I think that, at 600 horsepower, the Cummins' power curve is more evened out. Besides, although I don't know about the D-max, the Cummins is in 4 digit torque numbers by the time it gets anywhere near 600 hp.

Actually, I was under the impression that the D-max didn't put anything more than 300 hp in stock form, or was the 600 hp number you quoted a modified version?

I dunno...I've always prefered pure cast-iron engines that'll go forever