For the Money you are going to spend on JL Subs you could get some DC lvl 4 xl's or something like the FI BTL and i assure you they would run over top of the JL woofers man... What kind of budget are you working with??
Hell even the Sundown SA series woofers are very affordable and they are down right nasty woofers in the right enclosure with the right power
You could probably get 4 SA 12's for the price of 1 JL w7 lol