Select 'Options' at the Main screen and then press X on 'Game Status', pick the player you want to use with the X button and then press the L1 + R1 buttons together. Then enter any of the following codes and if you have entered it correctly you will hear a voice say 'Funky'. When you have entered a code you must press L1 + R1 again to be able to enter another one.
Select the 'Options' Screen at the Main Menu and then press the 'X' button on 'Game Status'. Choose your player with X button and then press the L1 + R1 buttons simulaneously. Then enter the code the following codes to unlock the corresponding effect. If the code has been entered correctly you will hear a voice say 'Funky'. Each time you complete a code you have to press L1 + R1 again to enter a new one. Unlock ALL Cars: LLA_KCOLNU
With the 2nd disc, select any stage and pause the game. Then switch CDs and if you've done it right then it will say across the top "V8 levels enabled". Replace V8:2nd Offense and wait for it to load. Quit the stage you were on, and then you will have the stages from the 1st and 2nd Vigilante 8!!