the dash has 31/2 the doors have 61/2 and the rear has 5x7/6x8. The 6x8's are the same as 5x7's they just have differet mounting rings. i know it sounds weird but they do. Hopefully i will be putting a better stereo in my car but im running out of money with other stuff (radiator, INSURANCE
ETC.) anyways... I dont recommend repalcing the 31/2s with coaxials. Im gonna put a component system in instead
. 61/2's in doors and seperate tweeters in the dash. Alpine component systems are awesome! Yes infinity, JBL, Polk speakers are good. ive never heard kenwood before. Crutchfield is good for installation plans but they can be very expensive. I wouldnt buy a reciever from them because you can find them much cheaper online. Sounddomain.com is a cool place for knowledge about stereos.
Later,
Nick