I currently have 2 cars I will be slowly upgrading the audio systems in 1 is a 2010 WV Jetta Sport Wagon, #2 is a 2003 Audi S6 Avant (yes another wagon)
The jetta is 100% stock, I have a Rockford Fosgate P300-10 all in one that I will be adding to it in the very near future to add in some much needed lower end, and then after the Audi is done maybe going back and doing an speaker upgrade if I can find some decent speakers that will be an upgrade for a decent price without having to completely redoing the entire audio system (the fiancee likes the stock radio system but we both agree the stock speakers are pretty weak).
The Audi current needs to be gutted and started from scratch... get rid of the circa 2004 Alpine touch screen in the dash etc and get rid of the Bose factory trash speakers. So I'm sure I will be on here quite a bit asking for advice on speakers, amps, subs, enclosures etc
I have upgraded head units, speakers, added amps etc previously, but I have never don't anything truly custom... so I have only used readily available fit kits, etc... I'm not sure how dead I want to go into the dark side LOL