hi, i have not seen someone wiring the power cable that way..(others are just normal wiring) It seems to be more troublesome..
try from battery, keep going along the passenger side, locate at black rubber look thingy at the wall, that leads into the car, cut a little opening(later seal back again), stick the cable into there, you will somehow know where it will come out from(inside the car).
(this is what normally people do, i think)
Hi Dannywss, powering the head unit direct to battery is troublesome for some but I did it so I force myself to remember to turn off the head unit and hide the detachable face and to isolate it from the rest of the car's electronics.
The Entry point and exit point are there to indicate diffcult wiring area where I had to put the wire into the chassis and come out somewhere inside the car (sorry if i confused you about the "exit point"), yes I normally have the cable along the passager side thats the easy part.
I normally have audio and power cables are on opposite sides so I dont get interference, I hated the engine sound in the speaker, very ignoring.
I know you know all that I have said above but I'm not sure which part you think is troublesome so I thought I explain my diagram a bit more.
Thanks for the suggestion, I was hoping I wouldn't have to cut anything but looks like I have to now.
Cheers,