: Easily created using 7-Zip by selecting "Gzip" as the archive format and "Ultra" for compression. Reliable Sources for PS2 ROMs (2026 Update)

The "UPD" in your search query ensures you are finding:

: A highly reputable source for "redump" collections. You can find pre-converted CHD sets here, which are already highly compressed and ready for emulation.

: An older compression method where the emulator must build an index file upon the first launch.

: A long-standing, safe site that provides games in a standard compressed format like .7z. How to Manage Compressed Files How To Shrink Your Rom Collection (The RIGHT Way)