TheGameSite: Tips, Cheats, Walkthroughs: N64: Extreme G 2
2064-Turns the bikes into planes.
SPIRAL- makes the camera spiral around your bike.
PIXIE - Takes away all the fog
NEUTRON - turns on/off the "Tron" mode.
XXX - Speeds up the game
LINEAR - Wire-frame mode
SPIRAL - Rotating camera
FLICK - Blurry graphics
SPYEYE - Overhead camera angle
XCHARGE - Unlimited shields and lasers
MISTAKE - Unlimited weapons
NITROID - Unlimited nitros
NOPANEL - Turns off the screen display