Infinite Ammo:
Press L1 + R1 + Down while playing the game.

Invincibility:
Press R1, L1, X repeatedly while playing the game.

All Drugs:
Press L1, R1, L3 repeatedly while playing the game.

Original Arcade NARC 1988:
To unlock the original arcade NARC you must collect the 25 Stash of drugs in USA.

Show All Stashes:
Press L1, R1, Down on D-Pad repeatedly while playing the game.

The Refinery:
Press L1 + R1 + Circle + X while playing the game.

Unlock Bonus Mission:
If you find all 25 stashes in Asia, a bonus mission is unlocked.