I am changing my Bose on 99 Max SE for a new system consisting of a Kenwwod KDC-mp819 head unit and a new set of infinity kappa 652.5i 6 3/4 or the 62.5i 6 1/2's my first question is which are the correct fit?the 6 3/4 or the 6 1/2's? i think it's the 6 3/4's but I am not sure.My final question is will i be able to run a 4 channel amp to these speakers and how much better will it sound compared to the Bose.Thanks