Dont upgrade back speakers spend that money on front ones. I've heard nothing but good things about the JBL MS62C(
An efficient way to search this site is in google type "site:caraudio.com XXXXXXXXXXX" X's being what you want to research itll bring up all the results just from this website. Good or better sites are around as well. Just in case that helps.
EDIT: Dont bring any threads back from the dead....
