Whilst I am personally skeptical of the results attained at Powerstation, that is a hefty hike on a like for like basis. Good efforts.
You accidentally stumbled across the best use of a dyno.

I would never use them as an absolute measure of power (except for pub talk). In reality, through (mis)calibration you can make them say whatever you want... but as a back to back comparison of the same car (on the same day) then they are very good.
You can say that the tuning box (assuming that was the only mod) added close to 20% power/torque to the Audi S3 in question without significantly altering the torque curve (apart from moving it up the graph

)...