I just replaced all the Sony factory speakers in my truck. I wanted to get rid of the factory muddy sounding sony speakers. I installed all new Infinity Kappa 6x8's. Wow what a difference it made. They are running off of the factory amp and sound great. I am sure if I ran them through an after market amp they would sound even better but I have other projects to do, and I just wanted something that sounded better then stock. I am planning on replacing the factory tweeters next. Here are the speakers I went with
Infinity Kappa 682.9cf 5"x7"/6"x8" 2-way car speakers at Crutchfield.com
Infinity Kappa 682.9cf 5"x7"/6"x8" 2-way car speakers at Crutchfield.com