I know alot about car audio, not about performance thats why i have to jump on one of these threads when i see it....
Three ways just seem muddier to alot of people, as far as a good set of componets to look into are the infiniti kappas/perfects(for the high end crowd) Focal, and mb quarts. I personally have the infiniti kappa componets in the s13. Slimmy covered the rest of my feelings on three ways(not lovin'

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Ill just hit the audiobahns. Alot of my friends have them and one of my friends is an audiobahn dealer infact so ive heard enough of them to make an oppinion on all their products. Audiobahn subwoofers are Loud and Unclear. We have benched some hellacious spl numbers w/ them but cant understand a damn word when just listening to them. Also if an audiobahn speak says its 2000 watts, i dare you to put 2000 to it. It'll fry in no time. Audiobahn amps also have a wattage problem, they dont put out nearly what they say. getting off subject. The speakers are very muddy. If you listen to alot of southern rap its not horrid, but other rap hip-hop rock electronica they are pretty bad on. but this is just my oppinion i say you go to a stereo shop and listen because all it takes is the right box size/port size to make ne sub sing.
:moon