opening in firewall?

I have a '94 Mustang coupe. I'm about to try to install a subwoofer and power amp in the back and of course I have to run a couple of wires for power, etc. from under the hood to the trunk. On past cars I've run them through the firewall with no problems but on this car I can't find a spot where the wires won't rub, etc. Any one have any experience and/or suggestions on running wires through the firewall. I'm trying to make this as painless as possible without taking the car apart too much. Any ideas for spots to try would be greatly appreciated.

Thanks!