I have a Bose system with toasted rear speakers. I'm looking at some new MB Quart 6.5 Premium speakers, but that's just from reviews I've read. What should I buy, and how should I install it? If I want to replace the front speakers too?

TIA!

You're best bet is to yank everything and start from scratch. Well, keep the HU if you want, but you'll need new amps as InfernoCL said to get the most out of your new speakers. And as for what is best, that is totally subjective. First get a price range then audition some and decide what you like best.

Like the rear deck and front door speakers?

You have to change all the speakers.... and change them to speakers with the SAME ohm ratings as the stock speakers (some are like 1.8 ohms... somre are different...) And you'll be lucky to find manufacturers that are making speakers with this ratings (ie......since NO ONE does this, and they SUCK)

If you're going to do it (in the S4) it's either change out EVERYTHING (all the speakers, + amp/amps) or replace with STOCK speakers. Pretty much those are your only 2 options.

Rian