True compression for the Xbox 360 isn't just about using a .zip or .7z file; it’s about using specific formats compatible with modded consoles (RGH/JTAG) or emulators like .
For storage or transfer, files are often "highly compressed" into .7z or .rar archives. These must be fully extracted before they can be used on an emulator like Xenia or a modded console. Storage Requirements xbox 360 roms highly compressed