Is it possible to mod xbox 360 games without jtag or anything like that if the game is saved to a flash drive?

i dont mean gamesave modding, i know everything you can do with that cuz i do that all the time with fallout and cod offline.. but like put in entire mods (meaning changing or puting in new game code into the game, and not the game save) like how theres physics mods for computer games, stuff like that.. but for xbox 360