My '04 factory set up was exactly the same way. My recommednation is to replace head unit, all factory speakers and add a 10" sub and tower speakers. That should fix your problem and improve your sound quality. lol
06 LSV
2 - 750lb Fatsacks, Custom Sunbrella Cover and Bimini, Kenwood KMR440MU and Amp Bazooka Tower Speakers, Aerial Mirror, Stargazer, 4 Port Heater.
Toys - O'Brien Natural, CWB Pure, IS Yellow Loogie, CWB Ride, Hyperlite Voyageur for the kids.