I built my first system in 1990, but I put a lot of thought into it. I started with an Alpine 7903 deck, 2 Fosgate Punch 45s (pre-HD), a Hafler MSE40di, a Coustic XM3 crossover, Boston Acoustice Proseries 4.1s, Sony XS-L6 mids with whatever the matching tweeters were, and a pair of Punch 10" subs in a sealed box.
All this went into my 1986 Merkur XR4Ti. The Bostons were driven by the Hafler, with the mids in the stock locations in the bottom of the dash, and vent mounted tweeters. The Sonys were driven by one of the Punch 45s, with the mids custom mounted into the rear side panels and the tweeters mounted in the c pillars. The other 45 drove the subs. I mounted the crossover in the dash, between the glovebox and the dash storage pocket. I could just pop the pocket out to access the adjustments on the crossover.
The first day I showed off that system, I was offered a job running an install shop by the manager of the store where I bought most of the components. I wish I'd taken the offer.
BTW, the crappiest complete system I've ever had is the one in my car right now. I'm going to upgrade everything from the speaker wire up in the next month or so. Still, considering the amount of sound I'm getting out my cash outlay of approximately $100, I don't think anybody would complain.