Yes this works on Official Firmware.ĮDIT 2: You can edit the game save as early as the first time you get to manually save I believe. Make sure to edit a save no later than when you officially arrive on the Normandy again (Right after you meet Samantha). The basic idea here is to convert your ps3 save to an xbox save, edit that save using Gibbed Save Editor, and convert it back to a ps3 save.
