If you have your own UMD backups (ISO files), you can compress them further using free tools. Here is the professional method:
A charming platformer that often gets overlooked, providing high-quality visuals within a tiny footprint. 2. Racing & Sports highly compressed psp games under 100mb
A flash-style puzzle game about a professional escape artist. The game uses hand-drawn 2D art and short looping music. A full rip is actually only 90MB originally, but highly compressed CSO versions drop to 55MB. Runs perfectly on any hardware. If you have your own UMD backups (ISO