I took out a roller and put in a solid flat Dwayne spec'd for me. I called Harland 2-3 months ago and asked about spring pressures and the tech told me. No more than 500 lbs of load, he said "although some people do anyway", but they don't recommend it". They designed them around flat tappets and hydraulic rollers. He said they'll probably live awhile with more but for longevity, they'll be a good rocker in the 400-500 lb of spring.