Got the 4 channel installed. The kickers sound phenomenal! With the amp they can get louder than I'm comfortable listening to without distorting. They've got a good amount of bass and now I've got to work on nailing down all the rattles in this thing. Should hold me over until I get the stuff for the sub install.
All I did was replace the front tweeters with a pair of MB Quarts that I had lying around. Didn't change anything else and it made a world of difference. The stock tweeters are pure junk. Add a sub and it would be a very quick and inexpensive improvement.
My understanding is that the dash speakers aren't tweeters, but in fact junk, small, "full range" speakers. They can't handle much range and they didn't cut out much mid bass from them and that's why many jeep owners blow out the dash speakers. In the future I may grab some actual tweeters that can block out the bass and wire those in with the fronts.
Thanks for all the help here guys!