I was look through Flash0 with file assistant and discovered a file called "version.txt". I saved it and brought it to the computer and opened it and it had info on my firmware (2.8), the build, and the target of the firmware (which was worldwide). Now couldn't a person edit that file so your psp believes its a Higher firmware version and it would play games that require higher firmware like GTA:VCS which most likely will require 2.81+. Its worth a try and may work. I'm not responsible if anyone tries this and bricks there psp. Its an Idea try at your own risk. BTW a person would need kernal access to do it on 2.8 but 2.71 may work. I hope this works and another idea is to delete crucial files that sony has put in for security of simply editing them.
target::WorldWide" thats what the text file "version.txt" said