I just wanted to give an update. I used to build home loudspeakers back in the early 2,000's. My actions here have a lot to do with what I learned back then. The front doors of the Mazda 3 sedan will not accomodate any normal commercial speaker. I was able to put 4" coaxials in the rear. The front has been a process. I replaced the front tweeters with a 3/4 inch cloth dome tweeter. The door speaker is a challenge. The plastic enclosure in the door will handle at most a 3" speaker with a mounting depth of no more than 1.75" deep. I experimented with a couple of full range drivers from Parts Express. I designed my own crossover. It took about 3 tries to get that right. It all sounds good but not quite right. The upper midrange has what some speaker designers call a "shouting" sensation going on. Music like jazz and classical sound great! Some rock and music with strong female vocals come on too strong and make my ears hurt after a half an hour drive. One of the drivers I tried had an aluminum cone and the other a fiberglass cone that was filled with poly. The aluminum cone driver was pretty hard to listen to. The fiberglass driver much better. It just isn't good enough for me. None of the PE 3" drivers that will fit have a paper cone. I am thinking that paper might be just what it takes to mellow out my mids. Kicker makes a 2.75" midrange driver the KSC270 that sounds like it might work. I ordered it today. I will report back once I have it installed.