Enter these while on the pause menu:
Left, Right, Left, Right, X - All Driving Upgrades Unlocked.
Up, Down, Up, Down, X - All Fighting Moves Unlocked.
Down, Down, Down, X - Bigger Car (must be in car before you enter it on the pause menu.)
Right, Left, Right, Left, X - All Gunplay Skills.
X, Circle, Square, Triangle - Show's Nick Kang's Current Location.
Bonus Characters: Create a license Plate using the codes below and then hold L1 + R1 before pressing X while highlighting OK.
FUZZ - Play as police officer Johnson
B00Z - Play as a bumster
5WAT - Play as swat
M1K3 - Play as a commando
TFAN - Play as Gangster_alt
HARA - Play as Asian worker
MNKY - Play as a street punk
Play as Snoop Dogg: Collect 30 bones throughout the game. Bones show Up as yellow on your map.