How much is 638 awhp on a Mustang Dyno compared to if it was on other dynos

 

bump

 

I have heard as a rule of thumb a Mustang dyno will read 10-15% lower, plus you are measuring true load on 4 wheels and both drivetrains so figure another 10-12% difference compared to a Dynojet that reads 2 wheels.

So possibly 20-27% difference would be my guess.