actually usually the Dynapacs read HIGHER. Churchs Automotive out in cali routinely puts out retarded high cars. Like a stock K20 RSX type-S making 260whp, i mean go read what they turn out. But dynapacs IMO usually read more between flywheel hp, and whp. Somwhere in the middle.
Case in point Knowledge Performance had a dynapac and someone had a b16 with I/h/e and it put down 172whp. I was like "no way, no B16 has ever made over 160whp with just i/h/e" at mainstream. I invited the guy to come to mainstream, he did, it put down 153whp. Almost a 20whp difference.
As for dyno dynamics, i do not know why they read lower, david has more experience so ill let him chime in before i assume and look like a dumbass lol