Invincibility
Pause gameplay and press L1, L1, L2, L2, R1, R1, R2, R2.

Full Ammo and All Weapons
Pause gameplay and press L1, L2, R1, R2, Triangle, Circle, X, Square.

Level Select
Play up to Subway A1. Return to the Main Menu and press Up, Down, Left, Right, Up, Left, Down, Circle.

Slow Motion Sounds
Pause the game and press L1, L2, R1, R2, Triangle, Square, X, Circle.

Elephant Gun
Pause the game and press L1, L2, R1, R2, then press X(4) then triangle (2) then square (4). Then you will hear a beepsound and you will have an elephant gun.

Unlimited health
Pause gameplay and press L1 x2, L2 x2, R1 x2, R2 x2.

8 Pain Killers
Pause gameplay and press L1, L2, R1, R2, Triangle, Circle, X, Square.

Unlimited bullet time
Pause gameplay and press L1, L2, R1, R2, Triangle, X, X, Triangle.

Health Check
You know when you put in the Invincibility cheat and you can't find a way to test if it worked? Well now you can! Simply pause the game, press L1 L2 R1 R2 Triangle Circle X Square. Then, un-pause the game and press Circle to use one of your PK's(Pain Killers). If your health goes down, it didn't work but if your health doesn't go down, it worked. The other way to check is to take a Bazooka and blast it right at your feet!(<- this one's the stupid one.)

Invincibility
While in game, pause and press L1, L1, L2, L2, R1, R1, R2, R2. Be careful though as it sometimes wears of when you come to a new level so watch your life if this does happen just enter the code again.