The EP350 will definately fill you space with plenty of pant flapping bass. A 10" woofer would do the job just as well.
Try checking Hsu Research (STF-2, and VTF-2), and Outlaw Audio LFM1-Compact. These subs are awesome performers, and they can be had for half the price of the axiom. Sorry axiom!
Check out the Hsu site. They have some tools in the FAQ section to help you pick the right sub for you space, and lots of reviews of there procucts.
Many axiom owners have a different brand sub.
Good Luck!
