I am new to the car audio world and was looking for any alternatives to the Mach 1000 system, or a link to a reasonably priced Mach 1000 system.
The Mustang lends itself well to any good system, the front doors hold a 6 x 8 and an aftermarket add on tweeter can be installed in the factory tweeter pod. Your options are huge. I would have no idea where to begin.
I just posted this door panel removal video in the speaker section of the forum. It'll show you how to get at those door speakers. http://www.caraudiotalk.com/audio-forum/showthread.php?12770-99-04-Ford-Mustang-Door-Panel-Removal