I am the 2nd owner of a 33' 2003 Southwind MH (affectionately named Dory). 2002 GM Workhorse W22 chassis. It only had 22k miles when I bought it a couple years ago and now I'm at 26K. Very well maintained by the previous owners. The one problem I had was a huge amount of sway at low speeds (speed bumps, turns, etc) and porpoising on the highway at high speeds. Since I traded up from a much older class A, I thought this was the nature of the beast with something this size.
We typically stay close to home but go out at least once a month. We live in the SF Bay Area (east bay-Union City) and usually head straight to the coast. Half Moon Bay is due west. It's just a 40 minute drive but we cross the San Mateo Bridge (9 miles, always a cross wind), and the Santa Cruz mountains which has curvy and steep roads.
I finally broke down and replaced the tires which were still in good shape after 9+ years but well past recommended life expectancy. A friend highly recommended replacing shocks when you replace tires, so I began the evaluations. Monroe-Not! Bilsteins-Alot of "hard ride" press. Koni's-I used them on sports cars for years, so lets try them. Lots of good reviews and nothing really bad, besides price. $170 each for the FSD's. I've been intrigued by airbags (too much hassle) and found airless bags called "Sumo Springs". They're a set and forget alternative. Just $200 for a set on the front. These had all good reviews so I figured I'd try those before springing (pun intended) for the $600+ rear set. Had the work done by Big-O tire locally. They had trouble figuring out which Koni to get but we eventually sorted it out. Great shop in Newark, Brian is the manager and was very interested in solving the problems and learning the results.
I do have to say, first test ride felt like I was in a different rig. All porpoising is non existent. Sway is completely gone! Ride is simply incredible. I can easily steer with one hand and the steering is much more stable and smooth. Here's what I attest to each component (sorry, many of you may want to know about one or the other separately but I installed them together)...
Koni's-Biggest impact on sway, smooth ride and steering. The special valving is for fast motions at low frequency, like pot holes and high frequency motion like expansion joints and other rough surface imperfections. With a smoother, quieter ride, I now have some noise gremlins to chase down (rattling cupboards and such). Never heard them before!
Sumo Springs-They replace the bump stops and "pre-load" the suspension with a progressive "spring" rate (multi density closed cell foam, actually). They're in contact as soon as you drop the lift. This contributes to stopping the sway (alot) and much of the porpoising (I suspect). I feel this reduces the work the shocks have to do, thereby extending the life of the Koni's (hopefully). They definitely stop that "bang" from potholes since the bump stops were just a bit softer than metal on metal. This is what caused the bang. No shock could stop that. This, and the sway, are the biggest benefit of the Sumo's, IMHO. BTW, the Sumo springs on the front just have one bolt and washer. Big-O did have to unbolt a brake or fuel line running along the passenger side frame rail to get to the nut but that wasn't a big deal. The line just ran up against the bump stop nut so you couldn't get a wrench on it. Anyone could do this.
Overall, I couldn't be happier with my 1K investment. Now I know I could drive across country without white knuckling and wandering in the wind.
Hope this helps someone!
BTW, I got Sumitomo ST 718 tires (19.5"). Good price point compared to Michelin's. Ride is fine so far.