These shocks added height to my Duster's stock suspension

Same deal as air shocks. You're just taking some of the weight of the car onto the shocks, which puts it right on the shock mounts that were never intended to carry the weight of the car.

Hopefully you checked to make sure your shock mounts were in good condition first. Eventually though they'll pound out just like they would with a set of air shocks. Only way to do it right is to re-arch the springs, everything else will end up biting you in the *** later.