From what I remember Pardos should be passable (without damage) in a stock Xterra as long as the mud flaps and step rails are removed.

For Slick Rock and especially Deer Valley sliders are mandatory if you don't want to damage your door sills. Patrick made it through Deer Valley in his stock height XTerra with full skid plates and 32" tires, but it took a while. With a 2+" lift, 32+" tires, and sliders Deer Valley is doable with an experienced driver, though even with that setup the XTerras sometimes end up needing a rear locker at points.

Here are a bunch of pictures of these trails from past XTerra trips (please ignore the Jeep ).

http://www.blankwhitepage.com/gallery/jeep_zj

- Matt