Just my two cents here...
we installed the front Sumo's when we first got our Vegas over two years ago now. We were so pleased with the difference in ride that we planned on adding the rear helper springs eventually. Well having completed that install in early July (a little complicated, as the factory floor bracing needed to be relocated and welded). We were very happy with the difference in the ride and handling on our first trip with the rig. Very little movement from other passing vehicles, road variations and crosswinds