adding a multi-channel amp 2 doorspeakers

I was wondering how you would put in a multi-channel amp in for my four door speakers.  I have 2 6" Kicker 05KS60's in both rear doors and 2 6.5" Kicker 05KS65's in the front doors.  (1 in each door)  I want to add an amp that will really boost their performance.  Suggestions and opinions on "size" and what would be most suitable of amps that would work would be most appreciated!!!

6.5" specs

There is pretty much an infinite amount of configurations you could go with in this situation. There is so many brands that will get the job done, so I'm not going to just type out a list.

You already have two sets of Kicker speakers, so get a 4-channel Kicker amplifier to handle the rms wattage of those speakers and your all set.