More Stuff
Pause the Game and enter these codes, you should hear "Impressive".
Maximum Health
Simultaneously press and hold L1, L2, R1, R2 and Select.
Refill Ammo
Simultaneously press and hold R1, R2 and Select.
Stuff
Pause the game and enter these. If it worked you will hear a voice say "Impressive".
All Weapons
Simultaneously press and hold L1, L2, R1, R2, L3, Select.
God Mode
Simultaneously press and hold R1, R2, R3, L1, L2 and Select.
Maximum Armor
Simultaneously press and hold L1, R1 and Select.