Ok, I know we're off topic quite a bit, but it must be said... I don't like saying anything on forums unless I know I'm 100% correct. And, no matter how much I argue the point, I'm only ever going to get flamed by people here that don't know what they're talking about. It's just the anonymous nature of forums unfortunately.
I have seen on many occasions, particularly GTR Skylines, especially R32's, where I have seen 600HP AWD cars make an extra 50HP in RWD mode.
As an example, a particular car down south, makes 990 AWHP and when run on the same dyno, because the ramp-up rate is so much more aggressive in RWD mode, it makes around 1200HP before it wants to turn the rear tyres.
Talk to any tuner in Australia worth their salt, and they will all tell you the same thing.