3.90 M3-33 to 5.03 problem

Okay, I have looked through numerous sites and just cannot find an accurate answer to my problem.

I have a PSP-2000 and a long time ago I made a pandora's battery and set the system to 3.90 M3-33. I use the PSP mainly for running emulators and running my PSX ISO's. Now the problem is, up until today I have had no problem running my UMD games. I went out and bought Monster Hunter Freedom Unite and it's asking me to update to 5.03.

My problem is, I am unsure what I should do in this situation. Is there a custom firmware that will allow me to run this game while keeping my emulators and iso's playable? I really don't want to have torrent and download a backup of MHFU just to play it.

Update your psp to 5.50 GEN, its still custom firmware and high enough to play it.

Thanks, though I actually managed to update it to 5.00 M33-6. Which works well enough for me. :b