Go to the dyno and break in the engine, tune it to the max, ask for an honest reading because your curious, get the paper work and then through it away.
It's way easier than most think. Look at and tune by RAW-uncorrected #'s, look at fuel consumed LBS/HR/BSFC.
For example: 550HP "uncorrected" would be 248 lb/hr fuel divided by the B.S.F.C (.45 in this theoretical case) at whatever the RPM was so= 248/.45 = 551.1hp
Then look at and understand the correction factor /C.F. and how that works. J.Rob