Ok first there's no such thing as to much bass it just needs to be installed right. Second for the setup that you're looking at from Bestbuy for $349 for that Sony setup you are paying $348 to much. In the car stereo world sony xplod bites as the subs are way over rated and the amps push no where near what they say they do. You can go to crutchfield and get the stuff but the only things I get from crutchfield is the installation components. If you are looking for a WIDE variety of components and all cheaper than most local stores go to
www.onlinecarstereo.com that's where I buy all of my and all of my friends car stereo equipment. If you want suggestions on what to get let me know how much you have to spend on the entire setup and how much of the rear space you are willing to sacrifice for subs and box. I've currently got on order a 15" square kicker solo baric, 2000w mono amp, 3 farad lightning cap, alpine cd player, pioneer premier 3 way 5 1/4 replacement speakers and will custom build the box for the sub myself. So just let us know how much you're willing to spend, how much space you want to sacrifice, what kind of music you will be listening to, and how loud you want to be.