The Loadlifter 5000 has "internal dampers" which by my measurements reduce travel by about 3 inches. As a result, every bump or dip in the road causes the ride to send a shockwave through the truck. It's as if the truck's suspension flexes with every bump - because that's exactly what it does. This applies with or without a payload, with or without a trailer. The only solution is to keep at least 30psi in the springs, which raises the back of the truck about a foot and makes the truck look like a fun car in a very bumpy, low-nosed stance. I had an air lift. Ride Control air springs on two of my previous trucks as well as on a homebuilt trailer and I really like them. But 5000s with bumpy bumpers make for a terrible ride and I worry about my truck - it's like driving without suspension. I never expected such a disappointing product from Air Lift. I'm switching to Firestone Ride Rite.