If you read SAE J1349, the real test procedure for horsepower numbers (revised 2004), it's simply impossible for a dynojet or any other dyno "SAE correction" to be accurate for two main reasons:

1) SAE correction procedures are designed to be done under very controlled conditions so as to minimize the correction factor in the first place

2) The actual correction factors are pretty complicated (vector cross products etc) and rely on far more information than what is normally supplied to dyno software. If you ever use WinPEP7, the Dynojet software, there's no way to input information such as the type of forced induction/intercooler, fuel viscosity, water temperature, etc.

 

Most use dyno numbers to compare timing changes, fuel changes, etc so small variations do not matter. Once you get your baseline number, you can still monitor the changes in HP/Torque as you make tuning changes. Most of the time the SAE and the STD on a dynojet are pretty close anyway. In the end dyno numbers are really just numbers to compare tuning changes so it's really not a big deal if they are off a few HP (except for bragging rights).

Anthony