Originally Posted by
number_6
You request that you want to exit departures; you can do this with the lounge staff (the easiest) or by contacting security. They will phone immigration and customs who will send an AFP (federal police) officer to escort you down to arrivals and to be processed. You will be well known to customs when you arrive. Transit security has nothing to do with this, other than stopping you from going from departures back to arrivals. At least this was the procedure the one and only time that I have done this, a few years ago.
Will they try to charge you the non-transit passenger charges then if you clear immigration as a transit passenger? I have a 15 hour SYD transit coming up next week and I'd like to hang around at the lounge for a few hours before going into the city. But I can't afford the ~100$ of charges I would get charged as a non-transit passenger.