http://www.dotars.gov.au/transreg/vsb/PDF/...es_3Feb2006.pdf
2.1 Choice of replacement engine - The power and/or torque of the replacement engine should not exceed the capaicty of the vehicle driveline.
There goes your RB30DET with an RB20DET gearbox.
2.2 Replacement components such as camshafts... engine management systems, exhaust systems, etc. are not permitted unless it can be demonstrated that the ehicle continues to meet the appropriate gaseous and noise emmission standards.
Note: the fitting of NOS injection systems is not permitted.
There goes PFC, most exhausts, cams, probably cam gears, unless emmissions tests are still passable. That also seems to say that removing your nos bottle is not longer acceptable.