Pioneer TS-A6857 will also work. They are 2 ways and sound pretty good. You need to replace your head unit as well. Most pioneers will run good off of a good head unit. The higher wattage and size you go the better,, and sensetivity. You can always shove 6x9s in if you are ambitious. Or do as everyone else says and get components. If you just want a easy upgrade, I recommend the pioneers or infinitys.

"Wow, that sank fast." "Yeah, like a rock."
96 Contour GL ATX
9mm Ford Racing Wires; 2 Resonators down, 1 to go;"Special airbox"; many mods planned
Sony CD player: 50wattsx4;remote;
Speakers=50 watt Pioneer 6x8s
Ross Evans smile