In latest issue of Auto Bild Sportscar Edition Sascha Bert drove Audi R8 5.2 FSI, Nissan GT-R and 997 Turbo on wet Hockenheim GP track.
Outcome? GT-R with Dunlops only 0.35s faster then R8 5.2 FSI(normal P Zero), 997 Turbo over 2s slower.
Acceleration wise? On wet track again 0-200km/h:
R8 5.2 FSI 13.4s
997 Turbo 13.3s
GT-R 13.8s