It seems the tomtom with a sd card reader will not see anything over 2gb.
Will a "micro" sd card 2gb work? as the normal sized ones seem to be hard to come by now.
You need NC 8.4xx or higher and Bootloader 5.5012 or higher for support of SDHC
Tomtom GO730 ,Navcore 9.004 ,Bootloader 5.5256 ,Map :Australia 845.2661ttmaps and Tomplayer on 16GB SDHC class6Password for all my files: downunder