Enter in cheat Menu:

Code    Effect
YAYCARS	All Cars
IMSPEED	Fast Start
VROOOOM	Inf Boost
R4MONE	unknown
TRGTEXC	Unlock Master's Speedy Circiut and Master's Countdown Cleanup
MATTL66	Unlocks all tracks and mini games
IF900HP	Unlocks all tracks and mini games
CONC3PT	Unlocks Art
WATCHIT	Unlocks Movie Clips