I own a 2001 GT and I have battled with the stock Mach system for years. I've replaced 4 amps now and would like to replace the whole system including the tweeters. The only thing that is not stock is the head unit which is a Pioneer FH-X500UI wired up with the Metra harness. My budget for the rest is around $500 - $700 and I would like something that sounds a lil better but at least as good as the stock setup, with a little more low end. I am thinking of using an 8" or 10" sub for space reasons. Any suggestions on speakers, amp and subs would be greatly appreciated. Thanks!