Factory holes cant be used. the GTR's piping returns to the drivers side of the engine, where as you know the rb25 piping returns from the passenger side.
I know of one for sale right now, off a R34 GTR and i think its around 400-500 bucks but apparently perfect nick.
so yes, cutting is required to fit a gtr cooler, i would look into other options such as the blitz and arc kits which dont require this