hi i have a 06 lincoln mark lt and sound system isnt bad but like to upgrade a little bit i was thinking of changing the speakers to infinity 682.9CF and was wondering if there much diff. over what i have know. im not sure if factory stuff is sony or if its just the subwoofer whats your opion .i do have a sony deck that made a good diff. in sound by itself.

also thinking about changing just the 8" subwoofer i know im better off changing whole thing but was wondering if i change just speaker how much better is it and what do you guys recommend .i heard filling box with cotton helps .