I have the Bils 20% stiffer in front and the "Heavy Duty" (stiffer) in back. I did this because I knew I would have steel all around, and the tire carrier adds alot of wheight to the rear.

The ride when the truck is empty is fine. At hight speeds I do notice the "bumpy" feel as you can feel everything on the road.

All around: I am happy with them!