this is my suggestion, and should be the first one anybody suggests on these kinds of threads. before you sell, trade, or buy anything because you want more SQ and less "boomy" bass. SEAL THEM. yes, some are made for ported boxes but that does not mean they cannot be sealed. you will lose output, but obviously thats what you want if you want less "boomy" bass. its the cheapest route, and will prevent you from doing something you might regret. IE -- buying new subs and wasting money, selling your subs and regreting it, trading your subs for something else that will leave you unsatisfied.
/thread