this is all exellent advice you are getting. invest in quality, amped, front components and your ears will thank you for it. if you have good components in the front with a good amp powering them you will not miss the real fill at all trust me, i know i don't. also keep in mind the more you separate the tweets from your mids the worse frequency response you will get. speakers are made to be listened to on-axis, which is pretty hard to do in a car environment so you have to do your best to minimize how off axis you are.