how bout there are much better ways to spend $500 for good car audio.
First of all stay away from Sony speakers. The amps are okay, not great though.
I imagine the 6.5's are for the front. Go with a decent pair of components. Then you can probably save what you were gonna spend to replace the 6x9's because now they will only be for a little bit of rear fill/soundstaging. Stay away from the bandpass boxes. They are not in the least bit musical, unless, of course, all you want is to "thump" down the street. Get a good 10" in a well made box. Maybe even make it yourself if you are handy with some woodworking tools. You can do alot with MDF. As far as amps, it's up to you, but beware of high power ratings. These probably aren't "weighted" and only serve to pump up the specs on inferior equipment.
Google "vifa" and you should find some decent speaker and prices.