Type at the title screen:

RUSH - Silly ships

Type at the main menu:

XTEAM - Enable Piranha team
XCLASS - Enable Phantom class
XTRACK - All tracks

Pause the game during a race and type:

PSYMEGA - Infinite weapons
PSYPROTECT - Infinite energy
PSYTICKER - Infinite time
PSYRAPID - Machine gun
FRAMERATE - Display frame rate