It's NSW.
there is no upper authority.
even if stock or engineered, the police can and probably will defect you.
they don't have to know if it is or isn't legal, they write their slip, and send you to get an inspection.
you go and get it cleared, by inspector/engineer, then head to rta.
you could be pulled over coming out the driveway, and start the whole process again.
good luck.