SOMEONE has GOT to write a tutorial on making changes to the sound system in these cars. We keep getting the almost-same questions all the time.

I'm not the guy to do it - I have no interest in 'upgrading' the sound system of my car. There are many threads on this in "Audio, Video and Electronics", here is a good one:
https://www.crossfireforum.org/forum...et-stereo.html