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.
'15 AW/SO F80 M3 6MT: IND cosmetic package, MS 15mm X 4, 3M crystalline, JB4, BMS intakes
'07 997 TT 6MT, Arctic Silver/Sea Blue: FBO, stock turbos: 5.9 60-130 E85, 997 platform record