Here are some cheats for the PSP users that don’t have custom firmware. Instead of having to install a special cheat device, you can just enter in these button codes to use cheats!
Buttons Referred To
To stop anyone from getting confused as to which button the cheats are referring to, here’s a diagram that clarifies that.

General Cheat Codes
Weapon Set 1
Left, right, X, up, down, square, left, right.
Weapon Set 2
Left, right, square, up, down, triangle, left, right.
Weapon Set 3
Left, right, triangle, up, down, circle, left, right
Get $250,000 Instantly
Up, down, left, right, X, X, L, R
Armor
Up, down, left, right, square, square, L, R
Health
Up, down, left, right, circle, circle, L, R
Raise Wanted Level
Up, right, square, square, down, left, circle, circle
Sunny Weather
Left, down, R, L, right, up, left, circle
Clear Weather
Left, down, R, L, right, up, left, X
Overcast Weather
Left, down, L, R, right, up, left, square
Rainy Weather
Left, down, L, R, right, up, left, triangle
Foggy Weather
Left, down, triangle, X, right, up, left, L
Spawn Rhino (Tank)
Up, L, down, R, left, L, right, R
Faster Clock
R, L, L, down, up, X, down, L
Destroy All Cars
L, R, R, Left, Right, Square, Down, R
Pedestrians Riot
R, L, L, down, left, circle, down, L
Pedestrians Attack You
Down, triangle, up, X, L, R, L, R
Pedestrians Have Weapons
Up, L, down, R, left, circle, right, triangle
Faster Gameplay
Left, left, R, R, up, triangle, down, X
Slower Gameplay
Left, left, circle, circle, down, up, triangle, X
Perfect Traction (Down Button To Hop In Cars)
Down, left, up, L, R, triangle, circle, X
Commit Suicide
Right, right, circle, circle, L, R, down, X
All Cars Are Black
L, R, L, R, left, circle, up, X
Spawn Trashmaster
Down, up, right, triangle, L, triangle, L, triangle
Guys Follow You
Right, L, down, L, circle, up, L, square
Chrome Cars
Right, up, left, down, triangle, triangle, L, R
Cars Avoid You
Up, up, right, left, triangle, circle, circle square
100% of MP Content
Up, up, up, triangle, triangle, circle, L, R
75% of MP Content
Up, up, up, X, X, square, R, L
50% of MP Content
Up, up, up, circle, circle, X, L, R
25% Of MP Content
Up, up, up, square, square, triangle, R, L
Upside Down Mode 1
Square, square, square, L, L, R, left, right
Upside Down Mode 2
Left, left, left, R, R, L, right, left
Nearest Ped Gets In Your Vehicle
Down, up, right, L, L, square, up, L
Lower Wanted Level
Up, right, triangle, triangle, down, left, X, X