I just installed Alpine Type R 6-1/2 component speakers. They come with 6x8 adapter for free. They're rated for 110watts each. I push 160watts RMS on each side. They sound great. Specially bass is fantastic. I did sound proof the doors. You can safely set your crossover point at 60Hz with them. In fact, if you don't have a sub, that's fine too. They can play down to like 30Hz in full range mode. There is also a 5x7 coaxial version, which is pretty cheap like $80. If you plan to deaden and seal your doors with something like dynamat+closed cell foam and your amp has the power they require, you will get pretty good mid-bass, mids, and highs from them. Otherwise, so much bass will rattle a lot of door panels and get otherwise lost inside of the door compartment. I heard that Kappa's might have a good mid-bass response, but a lot of people complain that their tweeters are harsh sounding.