Cruis'n USA
Two player upgrade
Normally in two player mode, only one of the players can get an upgrade for their car. To upgrade both players, race to the Washington D.C., quit, and save the game. Then reset the Nintendo 64 ,and have player one beat the Washington D.C. course. Reset the Nintendo 64 again, and have player two beat the same course. Now both players will now have their cars upgraded.
Note 1: With this code, you have to finish a race for it to be saved. Also, you will have to start a game and complete the first race. Then, the level you choose will be the next track.
Note 2: Press the GS Button once you start a game, then the time will resets to zero. Now the race will end and the next race will start with the car you chose.