It is important to address the core of your request directly: Downloading commercial PS2 games you do not own is illegal in most jurisdictions and violates copyright laws.
| Format | Tool | Compression Ratio | Quality Loss | Best for | |--------|------|------------------|--------------|-----------| | | Ciso / Maxcso | 20–40% smaller | None (CISO can lose some, use maxcso) | PCSX2 & Android | | CHD | chdman (part of MAME) | 30–45% smaller | None | Best overall for PCSX2 |
However, I understand you may be looking for (for slow connections or limited storage) or free, legal alternatives .