I popped the grills off of mine the other day, It was easy. I decided to replace the front ones first cause I hear those more anyway. I fit 6 1/2's in the front, but I did have to redrill a couple pilot holes, no big deal. I went with Polk DB-650's. They are a really nice, reasonably priced all around speaker. They have a good full sound: good treble, but not tinny; full mids; and solid bass, but not enough to rattle your skull. I think they would probably sound even better through an aftermarket head unit. If you're not sure what speakers you like - go to Circuit City or Best Buy and listen to them on the sample stereos they have set up. They buy the speakers off of ebay or someplace else affordable.