Originally Posted by A418t81
APR's dyno is a dynapak, which connects directly to the car's hubs with adapters. There are no wheels or tires on the car, only a pod at each of the drive wheels, in this case, 4. This lowers the drivetrain loss, you cannot use 20% for a quattro car in this instance. The S4 does make a solid 375 hp.
I have it from a pretty reliable source that the S4 doesn't make even 375hp. But it is more than per quoted.