Moon gravity:
Press Up(4), R1, Square, Circle at the main menu. The lower left corner of the screen will flash to confirm correct code entry.

Unlimited turbo:
Press R2, L1, Square, Circle(3) at the main menu. The lower left corner of the screen will flash to confirm correct code entry.

Hint: All bikes:
Successfully complete the hardcore part of career mode.

Hint: Endo:
Hold L2 + Square at a good speed and you will ride on your front wheel.

Hint: Moves:

Cliffhanger: Hold L2 + R2 and press Left, Right, Up.
Crack-Nac (Left): Hold L2 + R2 and press Down, Left.
Crack-Nac (Right): Hold L2 + R2 and press Down, Right.
Heart Attack: Hold L2 + R2 and press Left, Up, Down.
Indian Air: Hold L2 + R2 and press Left, Down.
No Hands: Hold L2 + R2 and press Up, Down.
Nothing: Hold L2 + R2 and press Down, Up.
Switchblade (Left): Hold L2 + R2 and press Right, Left(2).
Switchblade (Right): Hold L2 + R2 and press Left, Right(2).

Hint: Quick start:
Start your engine when the pre-race countdown reaches "3", then hold R2 when it reaches "1".