I'm sorry...I guess I shouldn't post that picture. That was the power wire when I first installed an amp in the truck. I see your logic concerning a possible fire hazard. Since then I've upgraded all my wiring (the main power line is now 2 ga). Since the wire is thick, I cut a hole in the rubber boot you see in that picture. Is that still ok or should I just drill a hole in the firewall and rerun the wires?

Also, I've neglected to add that I've placed plastic looming all around the wiring inside the engine bay including up to the firewall. That picture just illustrates where the wire would enter the cab and not how the finished install looked like. But thanks for your advice. I appreciate it.