You have to find a engineer that is Rta registered, I was talking to the police about it in sydney here after he defected my car, he said if I get it properly engineered by one registered with the Rta I could have my 20inch rims on my 33, but it has to be a legit engineer! So when the police punch your registration into the system it comes up with all the Rta info stated if its engineered or not. And they still defect after that u can take them to court and you will win!