This is an interesting one.
We have a '65 Coronet 440 that I picked up a few years back. It's a black 4-door car that my daughter loved. The intent was for it to be her first car...but not one she'd drive all the time. She doesn't like new cars and prefers the classics.
So I had a plan to build a system into the car that was largely hidden. I called DD Audio and had them custom build some 3000 series 15s. I ended up with a pair of their supercharged 3015 ESPs with dry carbon cones and dust caps with graphite logos. The idea was to just build a black trunk in the big, black Coronet.
Then we had a death in the family and I ended up with a '66 Chevelle in Malibu trim. Also a 4-door. Since the Chevelle was a much nicer and more mechanically sound car, the decision was made to put the effort into it instead of the Coronet.
The overall goal for the car is to update it with modern features that today's cars have like HomeLink, power windows/locks, a new gauge cluster that actually told you something about car, and a full sound system.
The ultimate goal for the sound system was to have a full build that is competitive at Finals...and I wanted it all to be completely invisible to the casual observer.
Nothing in the car should stand out as being an aftermarket item. With the trunk closed, at least.
A few pictures of the car the day I picked it up.