Downloading ISO files from unofficial "top" download sites can be risky. If you are looking for legitimate PSP games, stick to reputable archive sites like the Internet Archive or community-vetted safe lists.
If you've decided to stick to the massive library of actual PSP games, here is the standard way to manage your ISO files on a modded console: Homebrew on PSP (Part 2 of 2) | Games! subway surfers psp iso download top
You cannot download a Subway Surfers PSP ISO because it does not exist. Any site claiming to host it is likely unsafe. Instead, look for PSP Homebrew clones or play the official version on Android or PC. Downloading ISO files from unofficial "top" download sites