The thing is Audi have been sticking that Engine there for so long now they know how to set it up to work, I bet the first ones to use that were awful but as they made more they kept getting better until now they are amazing.
I was lucky enough to Drive an RS6 on Silverstone once and the kind of speeds you could pull it into corners in was amazing, Every part of me was wanting to brake but the car held and shot round like you would not belive, It doesn't feel like a large estate when driven hard.
The New RS4 is pretty hot as well, but my heart lives with the RS6 Avant.