Don't listen to MAD_DOHC. Speaker technology has barely advanced in 60 years, and in that time companies have figured out how to make decent speakers for not lot of money. Besides, anyone who thinks they're getting amazing fidelity in their car is fooling themselves. It's a car, not an anechoic chamber. Most speakers are either radiating directly into a piece of glass, or your knee. When you audition the speakers, keep in mind if they'll be bouncing their soundwaves off your glass, and whether they'll be boxed or use the whole trunk as an almost infinite baffle. The size of the box the speaker goes in changes the resonant frequency and Q. (which is the damping, or "tightness".) So use speakers in their intended application. Put a speaker designed for your trunk in a small box, and you get loose one-note bass. Put a speaker designed for a small box in your trunk, and bass output will suffer. (but I'm not going to explain over-damped right now.)