The latest version is version 6.1. the rx300 is generation 3. It is simple to change the disc. The nav box is located in rear on right side of the spare under the pocket. Its held in by four bolts. lift it up slide the cover over and hit the eject button. Put new disc in and put everything back. Done. Once you put in the new disc you CANNOT go back to the old one, it wont work anymore. So don't try someone elses disc.