On a MH, the Timbrens and Sumos will be preloaded at normal ride weight. They will eliminate the harsh bump that happens on normal road conditions, as they replace the bump stops, that the springs hit. I have Timbrens, both have a lifetime warranty. The Sumos are urethane, and the Timbrens are rubber. Both do the same thing, increase spring rate. Most people report a better ride and handling.