2004 Ford F-150 Suspension

I recently had a Readylift one-piece spacer leveling kit installed on my new body style 2004 F150 4x4 crew cab. Since I've had it (approx. 4 weeks), I've been hearing a noticeable rattling in the front end when I go over bumps (small and large), mainly small washboard style bumps on most asphalt roads. I took it back and was told that everything was working right, but that the hollow steel cone-shape design of the spring spacer would magnify the noise coming into the cab. I have a buddy that had his F150 leveled and he is having no such sound. Do you have any suggestions?