Start a one-player game, then pause and goto options. Select 'sound' and highlight 'FX volume, then press L1+L2. the game will now be 400% complete.
Havel all 32 Tracks
Pause the game then select the sound option. Highlight the effect option then press both left shoulder buttons.
Night Racing
On the circut selection screen, hold: L1+L2+R1+R2 until a headlight appears in front of the car. Now start any circut to race at night.
Upside down
On the circut selection screen, press and hold L1+L2+down+X. If it's worked, an arrow will appear under the track name. The racing veiw will now be turned upside down.