I'm surprised that that's not happening now for the aging GT-R considering cheaper car models like the Challenger and Charger Hellcat have already been running 700 HP right out of the showroom floor for a couple of years now...
Well, Japanese cars have always been short on horsepower and that's true of even in their top sportscars. For the longest time Japanese cars were stuck at the 300 HP mark since in Japan I think there were restrictions on horsepower and emissions that kept it that while. All the while Europeans and Americans were making 400 and 550 HP cars. I think this is still true today where the Japanese are somewhat stuck at 500 HP while everyone else is 600-700 HP. If it weren't for the hybrid system I think Nissan would still be there again because of the tough emission standards in Japan. This is also why Japanese cars are so easy to tune straight from the factory. Usually the engines themselves are underpowered for the work the engine are able to do at full capacity.
It's good to know this and maybe it'll force Honda to get into this horsepower game as well since their NSX is underpowered. Then again Honda is all about using the least amount of horsepower to accomplish the same thing higher horsepower can do. It has always been their model and I hope they keep it.