Is modding Xbox 360 games difficult or dangerous to the game/system/saved files?

Solution 1:

It is impossible to mod Xbox 360 (or more general, any console) games without jailbreaking it to allow unsigned content to run.

Besides that, games on PC have the advantage of being capable of running on hardware that is better than what the game was designed for. Meaning there's extra performance available for better graphics.

Console games run on a fixed platform and are optimized to run as fast as possible on that platform. That means they often run at 30 fps, 720p compared to 60 fps 1080p that most high end PCs can run their games on.

Making the game look better takes more resources, which consoles just don't have available for a given game.