Ok. In order to "cheat". You have to put your forza 3 gamesave on a flash drive and open on your computer with a modding software. Able to mod level and credits. Rehash and resign your gamesave. Put it back on the flashdrive. Plug flashdrive into Xbox move it back over to your harddrive and voilà. Up to 999,999,999 credits. Sorry for short answer in school on my iPhone.