U have 6x8 speakers and 8" woofers (basicly a small compact subwoofer) in the doors, and 6x8 speakers in the rear deck, the shaker 500 is a decent factory system, are you looking for louder base or just louder system over all?
Coaxial 3-way speakers are just fine for 6x8s, unless u want louder highs, the 4-way and 5-way have extra tweeters but same midrange as the 3way, i wont advise on those unless u run an aftermarket amp cause they wont sound good with the stock amp. i like coaxials cause of the price and from experience found out that u cant beat the sound, loudness or cleaness of a 6x9 5-way 460watt pioneer speaker (100$) with any other type of stand alone speaker unless ur gonna spend over 500$ on a propper set of componants
Componant speakers are speakers where the driver is seperate from the tweeter, it provides more flexablity for installation plus it can help raise the sound stage higher specially on door speaker locations where u mount the tweeter at ear level, but if ur gonna go with those u might as well keep the same stock speakers, cause its not gonna be louder but just clearer, and they lack a midrange so ur gonna miss out there, unless ur gonna spend 500$+ on high end componants and add seperate miranges and woofers, componants might sound superior than coaxial in certain setups but as a complete systems with mids and subs and a propper amp, coaxial have always been the cheaper alternative, and in the end it all comes back to preference and the type of music u listen to.
The best thing you can do is get adapter plates (crutchfield has em) that allow you to mount a set of component 5-1/4 speakers (or even sometimes 6.5" which would be ideal) in your factory 6x8 door and rear deck locations.
As far as speaker choice, my feeling (well, its fact lol) coaxial speakers (the ones where the tweeter is in the middle of the woofer) are inferior to separates (the ones with the separate crossover, separate tweeter and separate woofer). So thats the reasoning for using the adapters and going for separates. Clearer, better bass response, etc. If you decide on the coaxials though, im gonna say dont fall victim to the hype of 3 and 4 way speakers. Its just gimmicky.
Personal reccomendation...JL audio component speakers. I have em in mine wiht the adapters. I mounted the tweeters in the actual door panels because the 6-1/2 speaker adapters dont have room for a tweeter on the plate. Ill see if i can find a pic for you.
I would leave the door subs care they are powered by a internal amp which is crappy that you cant upgrade it. When I hold my 06 mustang I installed a DVD touch screen and let me tell you once you remove the stock radio and put in a aftermarket one the stock speakers sound great
i've got a pretty diverse taste in music.. mostly all types of rock though.. I'm pretty much looking for something louder yet not crazy expensive.. and I was looking into pioneer, alpine or infinity - but I don't know anything about audio systems so I'd probably just find good speakers at bestbuy and have them install it there..
what kind of in dash dvd-nav system will fit/is best?
Dont get them from bestbuy they'll just rip u off, its cheaper to get them online, and if ur only gonna replace speakers then do it urself and save on installation, its easy nothing to it, if u were closer to me i would install them for you, takes like 20mins to do
As for dvd-nav any dual din headunit will fit in you stang, i would stay away from pioneer nav systems, my friend got one and it sucks bigtime.