Regarding your enclosure.
I haven't specifically seen the response curve with those subs, but typically sealed enclsoures give you a pretty nice (flat curve) but they fade gradually and often are of little use below 40hz or so. Fortunately that covers the vast majority of the LF spectrum in commercial music.
If, however, you like some rap and the ultra LF stuff in some other music a ported enclosure can go a long way to help reproduce that.
The w3v2 (not sure how close it is to the old w3's) PDF sheet on JL's site shows that a sealed enclosure has an f3 of around 40hz, which basically means you wont' hear much below that. Ported gets you an f3 of about 30, so you'll get decent response into the upper 20's.
It's a common misconception that sealed=sq and ported does not. That's really not true. What IS true is that a lot of ported enclsoures (and bandpass) are optimized for the 40-50hz range and get really loud at that point but don't do much below that.
But a well designed, large, low-tuned ported enclosure often yields an exceptionally flat response and a lot of low frequency extension.
The trade off is good ported enclosures are harder to build and larger.