PSP dev Yoshihiro has released v3 of his now famous Game Decrypter. For those of you who have not heard, this lovely piece of homebrew allows users to play PSP games requiring OFW 5.55 or 6.00 on a lower custom firmware. This update in particular brings full support for CFW 5.00 M33-6 and 5.03 GEN, which was previously crippled. This update was made possible due to the recently released EBOOT.BIN patcher.
The best place to find a list of compatable games is still over at GBAtemp.
Download: Yoshihiro’s Game Decrypter v3
From the README:
hi guyz this tool is here for let you use your original game backup
on CFW 5.50 gen B-2 and 5.03GEn.
What's new ?
Comptibility with 5.03GEn is now complete (or not so far)
Thanxs to Revenge-crew for their patch on my v2 that i use for V3)
how i can use this tool ?
1 :lets go first you need to install the GameZDecryptZ folder in your X:PSP/GAME folder
2 : Open you iso with UMDGEN 4
3 : Go to File>File List>Export
4 : Save it as Filelist.txt
5 : Extract the EBOOT.BIN with UMDGEN4 in PSP_GAME/SYSDIR
6 : put your EBOOT.BIN extracted from UMDGEN PSP_GAME/SYSDIR and put it on root of your memory stick
7 : now you can boot game decrypter now you can press X 5 seconds later it's done 
8 : connect your usb cable check on root of your memory stick you have a new folder called decryptor
9 : copy the eboot.bin from the decryptor folder inside umdgen
10 : Go to File>File List>Import
11 : Choose Filelist.txt
12 : Select YES to forcing LBAs, then Save
13 : REbuild your ISO.
Enjoy it Yoshihiro
