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.