hooking up amp
behind the PCM on the passenger side of the car is a huge grommet where you can run your wires. I connected my ground wires to the rear seat belt bolt underneath the rear trim panels.
Grommet through the firewall is the EASIEST way to do it. For your ground, wire brush/paint scrape away some paint down to bare metal; shoot 3 screws through a ring terminal that is crimped (and preferably soldered) onto the end of your ground wire, into the car! 

