a) install a basic stereo, like a factory system..AM/FM cassette with pair of speakers

b) upgrade a factory system just slightly, adding speakers to get a bigger sound

c) upgrade to a system with CD player, amps and more speakers for audiophile sound, but not HUGE in volume.

d) install a pounding audio system that will shake the car

e) install a competition-quality system that will drive the neighborhood crazy."

I found this kind of funny but I know most people that have car systems usually just go straight for d.