all three cars have awesome midbass response. you can see/feel your pants move.all have front components that cost $500-$900. But $100 speakers would sound great in these doors.
all have external amplifiers on the speakers for plenty of clean power.
All have a combination of deadening, fiberglass bags, foam weatherstripping, and are fully sealed.
Deadening:
The van has 8 sq. ft. per door.
The accord and scion have closer to 20 sq. ft. per door.
The front doors are responsible for most of what you hear, and should receive more attention than anything else in the system. To duplicate this, you should budget 10 hours per door, start to finish. Can be done in half that time if you already know what you are doing.
some people say 25% deadener coverage is all you need and more than that is wasting it. i know a few acoustical engineers that would disagree with their marketing attempts. "buy my product and use less". Fact is, patches create multiple resonance modes. The industry tests damping and resonance by knocking on the panels. knock until the entire panel is dead and you have achieved your goal.
CCF is just to isolate the door panel from the door metal. could just be done where the panel contacts the door. instead of CCF, you could use fabrics like felt or fleece. buzzing isolation is just soft stuff between hard things. pretty simple.
closed cell foam doesn't absorb or block much sound (highs get blocked). open cell foam barely absorbs sound and doesn't block sound either. the next step is Mass Loaded Vinyl (MLV) for road noise blocking. but door seals themselves and the glass are larger sources once you do the above.