Which has the best sound quality? Which has more bass?

they are for the rear deck and im not sure if they will fit and i dont want to take my back deck apart if they wont work thanks alot
i already went to crutchfield and they said it wont work but i dont understand why not because they are 6x9 which is what is in there now i already have a aftermarket headunit

Any 6x9 will fit back there. But, if you have a factory premium sound system like "Infinity" or "JBL" you'll have to run new speaker wire or swap out the head unit at the same time.

Also, as a quick note, if you want to get more output out of those speakers, you may want to consider a four channel amp. Something by Audiobahn or Kicker would drive them pretty nicely.

Edit: I installed speakers for two years at Circuit City and trust me, they'll fit. You'll just have to use a 5x7 to 6x9 adaptor ring or cut the hole a little bit bigger using a multi-tool like a Dremel.