If it were only 1 speaker then wiring would be a possibility but chances are that if all of them sound like junk, your head unit is junk. Stock headunits are awful!!!! they only put out less than 10 watts a channel and the stock speakers are awful too. For a good entry level upgrade, look to pioneer on the head unit. You can get a decent unit on ebay for appx $100. As for speakers, you can check ebay as well or even (dare I say this) check Circuit City or best buy for some drop in 5x7's like some infinity reference or polk's. In the interest of money, only replace your fronts to start, that is the majority of the volume that you hear as the driver
