I got a set for the rear on my Nissan Frontier. Basically they replace your OEM bumpstops. So far I really like them. Obviously my personal experience is subjective and hard to quantify. I don't use sway control or WD with my 16DB. I don't notice the bump stops are are there except when turning while towing. I feel like the truck is more "solid" and in command of the trailer during on highway exit ramps and turns as speed. THey don't eliminate porpoising completely, but I think they do reduce it some. Mine were about $175 on amazon and took an hour to install myself with little experience.
http://timbren.com/timbren-ses/
ran them on my avalanche and liked them. wouldve kept them but had to go back to the oem bumpstops when i put lowering springs on it.
had to run airbags instead, but liked the timbrens better because of the simplicity
come to think of it, i still have them if anyone needs a set. would have to check if they are the same part number as your application though