I chose to post because i have some experience with AA's dyno and this argument is stupid.
AA's mustang dyno reads very low even compared to other mustang's. We all know this by now, any dyno can be manipulated including mustang's. But i know for a fact AA is legit with there mustang, it is there pride and joy for tuning.
To the OP, dont even worry about it. 20 hp gain with a software change is good for an N/A car! You can be sure thats a legit 20hp gain.