i would never suggest someone leave oem speakers in, just like randy said...get rid of those nasty things...if you put a nice set of components up front on an amp, and maybe an infinity basslink?
that wouldn't crack the neighbors glass, but it would pick up the low end, and be pretty cost effective...

as far as brand suggestions, go audition speakers...i dont know how you like your music reproduced, and i dont know your budget, shops love to audition their stuff, ask questions and maybe bring a couple of your own cd's to listen too.