Need for Speed - Underground - Platform: Gamecube

While in the Main Menu Screen, enter code: 
------------------------------------------
All Drag Tracks 
Right, Z, Left, R, Z, L, Y, X 

All Drift Tracks 
Left, Left, Left, Left, Right, X, R, Y 

All Sprint Tracks 
Up, X, X, X, R, Down, Down, Down, 

All Circuit Tracks 
Down, R, R, R, X, X, X, Z 

Have both the Katana and Dual GT Spoiler:
----------------------------------------- 
Play through the game normally, and once you beat 
Samantha's Big Tease (#77), pick the Katana Unique 
Spoiler. Now, to get the Dual GT, trade in your car 
for a Peugot 206. Then, trade your car back to what 
you had and now your car has Dual GT as the spoiler. 
To switch back for the Katana Spoiler, just go to 
spoilers and scroll all the way to the end, and 
there's the Katana spoiler! Once you do this, you now 
will have both Katana and Dual GT in the customize ride 
from the main menu.