Cheat mode:
Hold L1 + L2 + R1 + Triangle + X + Left when "Press Start" appears at the opening screen. Select the "Start Game" option and choose a level. Your character will have unlimited ammunition and will be invincible during game play. Note: The game cannot be saved when cheat mode is enabled.

Hint: More rage:
Hit a vending machine until the pop cans fall out. Stand over a can and press X to increase your rage meter.