To get good shocks costs money. You can try and see about the Bilstein 5150 series, you'll want a shock with a lot of fluid so that it doesnt over heat as your traveling over the bumps. I would do some researching with the jeepspeed peeps, you wont need the kind of shocks they use, but they can help you with more of a mid of the road shock in terms of performance.

I just got the Zone Nitro shocks and I like those. Just depends on your wallet and how much you are willing to live with. Also invest in some air/hyrdo bump stops, that will also help you with the ride or hitting those big bumps/dips.

I really want to make my XJ able to hand some jumps...it's just money right?