Make sure you look at the Correction factor on "Claimed" HP/TQ numbers on Dyno charts. There are two different correction factors used for correcting altitude and air temp when doing dyno runs.
In the upper right hand corner you will see "STD" or "SAE" which are the two most common. When comparing numbers these need to be the same. STD will read about 4% higher than SAE because of the correction
SAE: "SAE (Society of Automotive Engineers), USA. Power is corrected to reference conditions of 29.23 InHg (99 kPa) of dry air and 77 F (25°C). This SAE standard requires a correction for friction torque.
STD is Another power correction standard determined by the SAE. Power is corrected to reference conditions of 29.92 InHg (103.3 kPa) of dry air and 60 F (15.5°C). Because the reference conditions include higher pressure and cooler air than the SAE standard, these corrected power numbers will always be about 4 % higher than the SAE power numbers. Friction torque is handled in the same way as in the SAE standard."
If two dyno charts do not have the same correction factor, then you are comparing apples to oranges!!!
Thanks if you have questions just ask!