You need to put 500.PBP ( 5.00 OFW ) on your Memory stick root. Follow Prestige's little tutorial.

( Prestige rep + doesn't give you more rep all it does is protect you from rep -. Every 50 posts is 1 rep. If you get 1 rep down you have 1 less rep but if you have a rep + it is 1 protect from a rep -. )