I've just gotten a 2000 Explorer Eddie Bauer model and I find the Mach Audio muddy and unfulfilling. I'm considering getting Polk DX7 3-way speakers for the fronts and rears and swapping out the sub for an MTX Thunderform FEX10A amplified sub. Will this suffice or do experts out there feel that the head unit is so miserable that it must also be replaced to yield any significant improvement? The speakers/sub modification is a reasonable expense but I am afraid of spending much more than that. Advice is appreciated.