If you are able to increase your budget, OZ Audio is the only speaker to score a perfect score in IASCA comp. They run new +/- $300 for 6.5's + 1in Tweets.(W/X-Overs) I've been running nothing but for years, and been very satisfied. Oh, for the record, please don't over power your drivers. I mean, a "500 Watt" amp is simply not neccessary. (If it even produces that much) I am also A Big fan of MB Quarts, VERY smooth sound. But whichever way you go, Please go with components/seperates! Coaxials simply just don't cut the mustard. I ramble BTW, as for rear fill, think like you are at a concert. Where is the sound coming from? I mean, Who Really cares who's in the back seat?