Another vote for swaybar. I put them on everything I buy now, from cars, SUVs to trucks. I would try that. As far as shocks, I've had Rancho, Bilst and Fox. My vote is for some fox's with resevoirs if available.
Sway bars are certainly good to have on most vehicles. The truck has them stock front and rear, but it still looks like a pretty cheap option to upgrade the rear at least to a better one.
I looked at Fox, adjustable reservoir shocks seem ideal. But the price difference between them and ranchos/billsteins is HUGE. There also seem to be an overwhelming number of options with the Foxes. Do you have a recommendation that's a good balance of cost and performance yet still a big improvement over the more standard gas shocks? I will probably end up replacing the shocks at the same time the sway bar is upgraded, and both pretty soon.
