ive got friends who have cars in the 7 sec bracket (not skylines) but from what i can see and experienced dyno figures and the race are 2 totally different things , quoting a friend when i say dyno results mean sh*t! he got really poor results on the dyno then turned it around on the track with times.
like status says the other variables mean hell of a lot , track temp , overall weight of the cars, outside temps, track conditions , the better reaction time..
on paper id say the GTR but only the race will tell.