Compare the results APR achieved here with the RS7 to what they hit with the S8 on 100 octane which was 610 wheel horsepower. The 4.0 TFSI clearly gets some changes in RS trim for the RS7 and RS6 although Audi has not specified what those changes are. Regardless, the RS version is able to hit higher tune only numbers.
That means the lighter RS7 with more power to the wheels should easily eclipse 10.9@126 in the 1/4 mile the Audi S8 was able to hit. Mid 10's at 130+? That sounds well within reason.
Is the tune worth $3k? Clearly it is for the gains but APR is the only game in town and they sure priced themselves like it. The price will drop once others offer the same gains for less money.
Take a look at the dynographs and acceleration video below. Things are really heating up in the German twin turbo V8 tuning game.