here are a few cheats for grand theft auto liberty city stories on the psp.
Raise Wanted Level
Press L, R, Square, L, R, Triangle, L, R. A message should appear if entered correctly.
Rhino Tank
Press L(2), Left, L(2), Right, Triangle, Circle. A message should appear if entered correctly.
Health Cheat
L1, R1, X, L1, R1, Square, L1, R1. You should see a message, this also fixes cars while riding in them
Big Head Mode
Press Down(3), Circle(2), X, L, R. A message should appear if entered correctly.
Drive On Water
Circle, X, Down, Circle, X, Up, L, L.