APR takes their Stage 2 tuned RS7 4.0 TFSI twin turbo V8 to Texas and gets an independent dyno
APR made some jaws drop with their 680 wheel horsepower dyno of their tuned RS7
. Those numbers were with a preliminary Stage 2 tune only and the deletion of cats in the exhaust system, that's it. The dynamometer APR uses is a Dynapack dyno which is known to read a bit high. At the dyno competition at Texas 2K14 an all wheel drive Dyno Dynamics dynamometer was used along with a Dynojet for rear wheel drive cars. The results put the horsepower of APR's RS7 in context.
Now, the numbers are much lower than the Dynapack numbers. However, the Dyno Dynamics is known as a 'heartbreaker' and tends to read low. That certainly depends on how it is set. Regardless, the APR RS7 put down more power than a lot of cars and only one tuned GTR put down more power at all four wheels than it did. A modified GT-R put down 404 horsepower at all four wheels to give you an idea of how the Dyno Dynamics is reading.
Dyno numbers are not an exact science as this shows but the APR RS7 is making some serious horsepower however you look at it.