this is unfortunately so much more complex than u might imagine, riven, as going the seperates route can cause ur systm to sound like crap if not done right. But if you're PATIENT, have a good ear, follow a few basics and are at least a little bit savvy, u will end up in car audio nirhvanna! Having sed that, I suggest u try first to stay w/ a tweeter that is a close efficiency match w/ your mid or full range driver (hopefully u have that covered). Location is everything, too, as ideally u want the tweeters to both be in close proximity to ur mid driver, and to be pointed at or near your ears. Once that's covered, I strongly urge u experiment with crossover-if you're like most users, u alredy have an active x-over unit; if you're a dinosaur like me and prefer passive components, I suggest you plop down 10-15$ for a variety of mylar capacitors, from around 1.5uf to 4.7 uF, then keep trying different values till u get it right, being mindful of power limits. As for what specific brands will give u what u need, there are a lotta good choices-try looking in th april 2000 issue of car stereo review if u can find one (buyer's guide issue, kind of a bible), or go to speakercity.com, or parts express.com...e-mail me if u need more 2cents worth, will be glad2help...