I'm in the process of doing a rebuild, so the motor is out of the way. I want a clean looking engine bay. I've seen other stangs with virtually no wires. What do they do with them? Especially the large wire loom on the firewall and the starter solenoid. Where'd they go?
In the fenders. I think most of the loose wires have enough slack that they'll fit without lengthening. While you're in there, weld up all the little holes, prime and paint - will look amazing if you do it right.
Disconnect all wiring harnesses at their plugs, route them either behind the strut towers or into wheel well area via the open space near the headlights, then connect them in the middle.
The ones on the firewall you can tuck under the pinch weld and it'll be 95% out of sight.
Mansonozz did a nice job on the tech. I hide my wires last winter its actually very easy to do. It helps if its a bit warm as the wires tend to harden up in this brutal cold weather.
I don't know what year model you have but if you have a fox check out DUGAN RACING'S inner fender covers they go for about 170.00 dollars. But after you move all those wires you'll find you have what looks like a cheese grader and these things really clean all that up with very little work. If I can find the part # I'll let you know.