I have learned the hard way that the numbers from a dyno may or may not be accurate This happened several years back when Dram Dan from FL was still alive and had question some dyno HP results on one of my motors from the local Studka engine dyno. I took my 526 C.I. 440 dyno mule from Madras, OR(2500 Ft. elevation) to Klamath Falls, OR(4300 Ft.) to a DTS engine dyno. I made no changes to the motor and it made 100 HP less
on the DTS engine dyno that was less than a year old and was calibrated correctly
I took the motor back and told the dyno operator about the differences between the two dyno and we ended up calibrated it and it lost 100 HP also
There had been conflict between the former dyno operator and the dyno owner so it wouldn't surprise me that he had mess with it before leaving
My message is don't worry about the net HP and torque, look at the differences between changes you make, if it is getting better your going the right way, if it is losing power go the other way