you are alowed to fit a rb26 to any skyline r32 onwards... i was worried about it when i did it, but then i just went to vicroads and registerd the numbers... only thing u gotta worry about is if the engine fitter doesnt noe what hes doin and starts choppin sh*t like cooler holes etc... thats when you'll get defected and then need to get an engineers report, if its an N/A and your either changing the motor or replacing it with a DET all you gotta do is notify vicroads, but again having the larger brakes is of your own concern not vicroads...