Recommendations for a car stereo set-up?

I put a set of Pioneer 6x9s in the back of my Pontiac Grand Prix two years ago. They were $65.00 at Meijers, same ones at Best Buy were $80. Have Dart parts stored in the old box, the speaker model was TS-A6963-R. I listen to Rock kinda loud and they sounded really great, esp. for the price range, and held up well over a year. Sold the car last fall. I'll probably get the same speakers for the 67' Dart if I don't like the newer Sony's(w/ ugly space age covers) the last owner installed. We'll see, gotta get the car running & on the road first.