So much for just replacing the speakers...can't get there from here. You're ending up with a full-on audio build. Don't worry we all started out "with just the speakers".
LOL. Yeah. Well, I'm done with audio upgrades. A tuner is next on the list. Changing the door speakers helps a little bit if you already like your Sony system, which I did, but the bass will suffer as the new door speakers will make everything sound brighter. The only good solution for the sub is to put a bigger dedicated amp with a new sub. Swapping just the speaker is most likely not going to do much.
I knew that, but wanted to try to get away with as little spend as possible. I also wanted something that fit in the stock location, as I was not ready to give up any more space. Those $450 I would have rather spent on something else. But I have to say wow, what a big difference. I am sure that another grand or two on more amps, better speakers, etc. would be sweet. Maybe in a year. Or three.