If you see websites or video tutorials offering an "extra quality God of War 4 PPSSPP ISO," you are usually downloading one of two things: 1. Heavily Modded PSP Titles (Texture Packs)
Be very cautious of sites claiming to host a "Direct Port" of GOW 4 for PSP. These files are often malicious or empty. Stick to reputable emulation forums for your mods and texture packs.
