The thing is you can use the Veyron as a everyday car and not many things will go wrong as its stock. Whereas a skyline pushing that much power... If it is driven everyday your going to get more and more issues arising. Its impossible to drive that everyday without having to replace components every so often.
My Brothers Evo got mapped a while back and dyno'd he is pushing 430bhp now, he is now working on another engine he has spare which he will be dropping in but he is tuning that to 800bhp, he cant simply just pop that into the car and drive it, everything will need to replaced! Its hardwork. He strips his engine every certain miles and cleans it/rebuilds etc... Im guessing my man with the skyline is constantly working on that!