Hi all....my 2004 SR5 has the worst sounding stock system I have ever heard. Muffled... no highs..no pep! If I put the fader to the back speakers only, well....muffle city! Anyway, went to two custom stereo shops and they both recommended swapping the speakers for Alpine type S speakers which sounded nice in the stores, had a nice sharp treble. Anyway, yesterday I had 4 of those puppies put in (6x9 fronts, 6 3/4 rears), and although the fronts have a slight improvement (not much!), the rears, are still muffled and cloudy... terribly! I have always left my stock units in my Jeeps, hondas, etc., but this one is just awful. I figured some of you have dealt with this frustration also and might share how you "overcame" this problem----new head unit? add an amp? could they be defective rear speakers or just the wrong kind? Thanks guys!