I've checked about 5 sites, and I can't find what that amp puts out to the sub...even directed's site didn't seem to say. So, I can't reccomend a sub.

As John said, its going to be tough to get 'low end' in a Wrangler...you don't get the cabin gain you get from a car. Depending on what kind of music you listen to, I'd suggest a ported 10 or pair of 8's, or maybe a bandpass.

Toby