Which dyno to choose for tuning ?

Hello , i am opening a dyno tuning shop, was wondering which dyno gives more realistic WHP numbers to the real street condotions between dyno jets and mustang jet. I know the different between there corrections and load systems and from what i understood that dyno jet will give you from 10-15 % more hp numbers than mustang dynos. But isn't the mustang dyno load system gives more realistic street condition hp numbers ?

Thank you