Im doing an audio install on my 2000 Audi A6, and i can't really find a place to run my 4 gauge wire to get through the firewall. Once i couldn't find a place, i tried going through the little space between the door, fender and hood....but theres a plastic piece of some sort blocking it. im puzzled please help! also, does the stock headunit have a line output already? cause i bought an LOC, but after reading the manual, im not sure if im going to need it.