Unlock Sound test
     Enter "ART88" or "MUSIC" as a player name.

Get $50,000 
     While  you  are  at  the course selection screen, hold Select and
press II to get money.

Unlock Special course 
     While  you  are  at  the course selection screen, hold Select and
press Left to access to the Special course.

See winning time 
     While  you  are  at  the course selection screen, hold Select and
press Right to see winnig time.

Sounds select:
     Hold  Select and press I or II while the game is paused to select
any music.