2003 350 GT V35 Skyline - DVD/Sat nav HELP. Japanese to English menus and GPS

[Andy_V35Sky_350GT]

Hello, I recently bought a 2003 V35 350GT Skyline (origin of which is Japan of course, I live in Australia) and, to be expected, the standard/stock DVD/Sat nav system is in Japanese. I know the system wont have any AU maps, but I would love to get the system into English so I can have easier use in using the fuel milage and compass features, etc etc etc.

I cannot seem to find a brand name (except for something that looks like ETC) anywhere in the options or menus etc etc etc, and I would GREATLY appreciate any imformation anyone can shed, no matter how big or small. Even just a brand name or some kind of information.

Is it just possible to update the firmware? Or maybe even change over to English 350Z model?

*NOTE* I have posted this on both the Skyline and 350Z forums because of the similarities between the two models.