i was thinkin and... why does the box for a ported woofer have to be bigger? can't you ajust the port to make it the same in a smaller enclosuer or does the air space have somethign to do with the sound?
in most cases, the smaller the ported box...the high freq the sub will peak...and the larger the box, the closer to your tuning it will peak (in respect your tuning freq)
ex...2cuft box tuned to 30hz, may peak around 40hz (depending on the sub)
3cuft box tuned to 30hz, may peak around 35-36hz.
some subs actually like relitivly small ported boxes...Type-r's come to mind. Others like huge boxes.