Game Shark Codes:

     Unlock Crystal Cup - 802CB4A9 0001 
     Unlock Diamond Cup - 802CB4AB 0001 
     Unlock All Cups & Tracks - 
          802CB4A9 0001 
          802Cb4AB 0001 
          802CB4AD 0001 
     Unlock Scorpion Car - 803DF94B 0001 
     Unlock Cobra Car - 803DF94D 0001 
     Unlock Cheetah Car - 803DF94F 0001 
     Unlock Panther Car - 803DF951 0001 
     Unlock Challenge Mode - 803DD109 0001 
     Unlock Cobra Challenge - 803DD10B 0001 
     Unlock Cheetah Challenge - 803DD10D 0001 
     Unlock Panther Challenge - 803DD10F 0001 
     Unlock Super Challenge - 803DD111 0001 
     Unlock All Challenges - 
          803DD109 0001 
          803DD10B 0001 
          803DD10D 0001 
          803DD10F 0001 
          803DD111 0001 
     Unlock All Cars - 
          803DF94B 0001 
          803DF94D 0001 
          803DF94F 0001 
          803DF951 0001 
     Infinite Credits - 80388C1D 0003