The stock running boards did a great job of keeping the sides of the 4Runner rock chip-free. As soon as I removed them and installed rock sliders, rock chips started showing up in the paint. I took one trip to Death Valley with the open rock sliders and picked up about 40 rock chips per side. (Traveling hundreds of miles on gravel roads at speeds up to 83 mph (by gps) does a great job of blasting paint off just about anything.) In an effort to preserve the 4Runner's paint I cut out steel inserts and welded them into the voids of the rock sliders. Here is the result:



It took a lot of work to match the bends of the sliders. Tubing benders have a tendency to push the outside of the bend further out before bending it inwards (if that makes any sense). Stubb's sliders are built on a jig and have extremely high quality control, but each of the six steel plates were still just slightly different. The welding itself took no more than about 15 minutes.
So do they work? Shortly after completing this project I took a trip to the desert (Joshua Tree) for 4 days of wheeling. Even though the sliders had 2-3 coats of primer and 6 coats of paint, the gravel blew through it all and left me with this:

You will note tons of chips in the bottom of the plates, and yet none of those rocks made it up to the body. Keep in mind those chips are from one extended weekend of wheeling, so clearly over the lifetime of the vehicle the paint is going to stay much nicer.