Here's a summary of the details from the thread for you guys:

TT-R = 2.5 inline turbo 350bhp, RS4 wheels
RS5 = V8 470bhp, A3 Clubsport-like bumper
R8 = V10 520bhp
Q7 = V12 750lb-ft tq, huge ceramic brakes

Most of this info has been discussed in recent times on many forums. The only reason I'm not calling those guys liars is because they have been on the forum for years and have lots of posts. Hmmm... Can anyone confirm?