On Disc One, when you visit the Wolfpack Gas Station, enter the shop and go into the back room. In there you'll hear Richard Jacques' 'California Demon' playing on a radio. 'California Demon' is an original song by Jacques that first appeared in Bizzare Creations' 'Metropolis Street Racer'.
Beating the game, another option will appear. It's the Heahunter V2. The game has some changes and the difficult is harder.
Shoot out the lights first, but since Ramirez has a powerful gun, run behind one of the containers. If you have a good view, you will see him point his gun away from you. This is your chance to attack. Give him everything you have for a moment, then duck back.
Note: It is important that you jump at a certain point. If you jump too soon or to late, it will not do any damage to the door.
To access the Star Locker at the L.E.I.L.A. office, beat the records in all the VR Missions, then beat the game. A message will appear at the end of the credits telling you that you have unlocked the secret. You'll be able to access the Star Locker in V2 onward. Inside the Star Locker is every single weapon in the game, with unlimited ammo.
Warning: Opening the Star Locker at any time will permanently mess up your game, as you will be unable to pick up vital items in the game.
On any mission with an gate type elevator door, open the elevator by pressing the A button while crouching with the L trigger. You can now pass through any wall on that loaded stage.