I installed a seperate wireing harness, running wires from the head/eq in the left gutter and rca cables in the right one. To keep wiring to a minimun, I did, however, tap into the fuse block for memory. For noise reduction, I also have a closed loop ground--grounded to a OO welding cable--for all the components, rather than chassis grounds. The seperate wring harness allowed me to keep the origional harness unmolested.
The remote solenoid, trunk mounted battery eliminated the need to find a way through the firewall.
It's a little dirty because I have other issues to address. But hey, this installation was done 18 years ago this August. I also have the vented battery box removed, something that helps clean up the look.
Here's 300 watts worth stuffed in the trunk. Measure behind the seat and see what challenge goes into mounting a 12" sub behind the seat. I also have a remote 6 disc cd changer, just to the left.