The theme data is stored on the SD card, and if it's removed you'll get the default theme. Is it possible to: Install themehax on one system, move it's SD card into a different (same firmware) 3DS and have it work? Install themehax onto your SD card without the use of any exploit at all, just by putting the files in the right spot with a PC? I'm suspecting 1. won't work as-is since the systems have different profiles, but if the files are renamed to account for that would it work? Perhaps (probably) some theme information is stored in NAND too, but shouldn't it still be possible to set a theme normally and then replace it's files with the themehax files?