Hard Drivin' Cheats

Finish a regular game, then go into the Options menu and change the race type to Practice. Then enter the following code....

B + C + Start

If done correctly you should have traffic when you play in Practice Mode

On the championship lap of the stunt track, turn left rather than going straight. You'll go through the signs and find yourself facing Phantom Photon on the speed course, where your chances of beating him will greatly improve.

Play a normal game and lose on purpose. Now go to the Options Screen and select Practice Mode. There will now be other cars on the track with you.

Run into the cow at the beginning of the stunt track, and you'll hear her moo.