Sound qaulity wise they aren't bad for a factory system, however you are quite limited in changing things out while retaining alot of the factory parts.
What I mean to say is that, changing the speakers and not changing the amp will have little effect on what sound quality you will get.
There are the kicker audio speaker upgrades which are a plug and play option from mopar, while I haven't used them myself personally they do exist.
The speakers in the BA system are 2 ohm so it really limits you on what you could change out while leaving everything else the same.
What part of sound quality to you feel is lacking. The front tweeters in the dash handle most of the vocals and high frequencies, if anything I would think they would be responsible for an increase in sound qaulity if changed out, however if you start changing things out, its pretty much remove the entire boston acoustics system and go aftermarket.
For myself I find the sound quality just fine, I just thought the bass was lacking a bit and added a 10" Kicker L3 sub in the back trunk area.
Let me know if you have any more questions.