I am going to re-route the cables that run across the intake to be mounted on the firewall. Is it OK for me to drill into the upper firewall, above the intake manifold? Or will I start tearing into things? Are there any spots to watch out for so I don't destroy something on the other side of the firewall?

 

If you drill into the firewall there, how in the world are you going to even find it on the inside without taking the whole dash out?

 

Good point, but I should have been more specific. I'm not going to pass the wires through the firewall. I want to drill small holes so that I can mount the wires ON the firewall. I am planning on using those black plastic loops with the spike on the bottom that holds stuff secure. You know what I'm talking about now, right?

 

Chances are that a small hole for a short fastener would not have a problem, but I don't know how you would be absolutely sure without knowing what was on the other side.