I have a set of rear helper coil springs wich just bolt on replacing the rubber bumpstops, it says they work to help the leaf springs when the vehicle is loaded or hauling to level it and prevent bottoming.

http://i281.photobucket.com/albums/kk230/rrodriguez4x4survivors/Picture862_20Sep08.jpg?t=1222991505


http://i281.photobucket.com/albums/kk230/rrodriguez4x4survivors/Picture863_20Sep08.jpg?t=1222991619

http://i281.photobucket.com/albums/kk230/rrodriguez4x4survivors/Picture865_20Sep08.jpg?t=1222991645

I do carry overweight on the rear and already have a extra leaf spring, will this coils work for high speed off-road (ripples, jumps and bumps) or they will just make the suspension stiffer, rebound more or any other side effects?