We have the cheap speakers in the ceiling. Can those be replaced with better speakers? Do they make better ones that would fit the same way? These are the small white ones...
I went with Polk also but bought 5.25 instead of 6.5". Fits but barely covers holes. They do sit flush. Best thing to do is put in an amp. That will improve sound while pushing the better speakers. Low cost 25watt/ch x4 amp will do the trick.