hey im thinking bout getting to 6.5 apline r type speaker and to 6x9 apline r type how will that go with the kickers current model 4 channel amp or should i go a diffrent type of speaker??
focus on your front stage, and don't worry too much about the rear speakers... http://glasswolf.net/papers/rearfill.html
if you really want rear speakers, use a low pass filter to block the high frequencies. Tweeters in the back will wreck your sound stage. If those 6x9's are 2-way speakers, then they have a tweeter. http://www.the12volt.com/caraudio/cross.asp
what's the RMS rating of that 4 channel amp? is it at least 40 watts RMS @ 4ohm per channel? if so, you could use the front channels to power a set of component speakers in the front, and bridge the rear speakers to power a single sub in a well built enclosure. That single sub will sound much better than what any 6x9's could ever put out.