Downforce

At the main menu, press:
Invincibility - L1, Triangle, R1, Triangle, Down(x2), Circle
Expert CPU    - Triangle, Right, Left, Square, Up, Circle, Down, Right
Crash Arena   - Left, Right(x2), Square, Down, Triangle(x2), Square
Crash Arena in 2-plr mode - Right, Left(x2), Circle, Up, Triangle(x2), Square
Beginner Trophy - Right(x2), L1, Triangle(x2), R1, Right
Intermediate Trophy - Right(x2), Square, Left, L1, R1, Square(x2)
Expert Trophy - Right(x2), Circle, Left, L1, Circle, R1, Circle
Intermediate Championship - Down, Square, Up, Square, Right(x2), Left
Expert Championship - Down, Circle, Up, Down, Circle(x2), R1, L1

 