Subwoofer and amplifer install in 2009. I need help!
 

Where can I find a hole in my firewall? I have traced all the wiring under the hood and all can find is wiring going through the fender. Please help!

If it's not too late, here you go.
 

When I put my system in, I just poked a hole through the steering column rubber. I used an old sharpened antenna from an old patrol car (we have a bunch because my dad works for them) and just electrical taped it tightly as we pushed it through. It comes through right where the other wires are coming through their pre-drilled holes in the frame. Hope this helps!

I think, whatever you are doing, just need to have a consult with an expert, who has done this kind of actions, it is really fruitful for you.