Beat the game to unlock the following:
-"Big Heads" and "Infinite Ammo" cheats in the Options menu. Note: Activating a cheat will prevent trophies from being earned.
-Tesla Cannon and Spreadgun
-Civilian, End, Mall, Light Armor, Medium Armor, and Old school costumes.
Have a saved game file from Army of Two on the PS3's hard drive or memory card to unlock the AS-KRI and Grand Pinger for purchase.