The sumo springs replace the regular bump stops which are a dense high density foam material. The sumo springs compress well compared to the regular bump stops that don’t. So first of all, I replaced the bump stops with the sumo springs and took it for a test drive. The improvement I found on my short run was minimal. There was an improvement but it was less than I hoped for. However, I did test them over quite a rough road. The next step was to replace the oem shocks with the Rancho 9000s. What a difference! The combination of the two smoothed out the ride in all terrain. I have been using the combination for over 4-5 months now and I highly recommend the combination for an improved ride. The original shocks are so bad that no matter how well the sump springs compress you will compress them to the bottom. The sumo springs come in three levels of density. The ones I have are the softest version. Now I didn’t change the rear bump stops but changed the shocks all around.