PCSX2 natively supports .gz files. You can use 7-Zip to compress your NFSU2 ISO into a GZIP archive. While it saves significant space, the first launch may take a moment as the emulator builds an index. How to Get a "Highly Compressed" Working File
Originally created for the PSP, this format is widely supported by PS2 tools like Open PS2 Loader (OPL) and emulators. It can reduce a 3 GB ISO to roughly 1.5 GB–2 GB depending on the game data. need for speed underground 2 ps2 iso highly compressed work
Traditional compression (like .ZIP or .RAR) requires you to extract the file back to its full size before playing. However, modern emulation has introduced "on-the-fly" compression formats that save space while remaining playable. PCSX2 natively supports
Currently the "gold standard" for emulation. It offers better compression than GZIP and doesn't require extra index files. How to Get a "Highly Compressed" Working File