there are a lot more variables with the dynopack, and the dynojet gives you a better overall view of the power your car is really making without the ability to hone in on certain areas, and introduce additional variables. I believe the dynojet will give you more of a real world idea of the performance of the car as a "sweep" thru the powerband. I know there are some lurkers here who can explain the dynamics better than I. Really, the ultimate judge of horsepower (all other things like gearing and weight being equal) is how fast your car goes in the 1/4 mile, despite the utter distain that some folks have for that venue. Take care, Mark