Battery to amp power cable wire routing question

Pat C.

Hey guys, have most of the pieces to where I can finally start the install of my amp and head unit which should be to my house this coming Tuesday. Had split the order in half on purpose. I do have the JL amp and all wiring to run for powering up the amp.
All info I've been reading back through here on the forum is telling me to run the 4 AWG power wire back through the OEM cable shroud to the rear of the battery.
I agree with this versus running from the battery over and down to the grommet below the brake booster. Less exposed (to the elements) wire = less long-term problems.
My question is in regards to where this wire will come out at in the interior. Will it come out "below" the dash, or do I have to pull part of the dash apart to retrieve and run the remainder of the way to the rear of the car?
Am very apprehensive about getting into the airbag section of the vehicle. No doubt many of you have fished the wire through this boot. Just need an easy explanation of where to look on the interior firewall.
Am also assuming everyone is installing the amp upright behind the rear seat divider??????
Appreciate the help.
Pat