yep, power to weight is the winner.
belive that an R8 is around 1800kgs, giving 7.38kg/rwkw
if a stock GTR is 1450kgs, then to match a 7kg/rwkw, the GTR will have to make 207rwkw.
I reckon a stock GTR will make around 180rwkw, so with an exhaust it will be close.
plus don't forget rear wheel vs 4wd - will the R8 get the power to the ground efficiently as the GTR?
all so many variables.