I saw a dyno operator (Richard Holdener IIRC) explain that the numbers taken at the very bottom of a dyno pull can't be regarded as accurate because of the way the dyno is loaded and the throttle is applied. This is why you sometimes see a dip in the curve immediately after the start of the pull and then it comes back up. Anyways... I would bet that using 273's examples of the 360 300 hp vs 380 hp ,even though the numbers may be similar at 2500 , the 380 hp would be down a fair amount at 2000 . 500 rpm can be significant when we're talking long overlap cams.