Not really necessary, I have the HD pack on a long-bed frontier with a Leer shell. I have not installed the final leaf. Even packed full of food, gear, water and gas, the truck rides much better than the stock suspension. Unloaded, but with the shell, it is comfortable and the rear tires are always on the ground, not bouncing. I wanted to have the option to upgrade if I needed, but the extra leaves are now sitting in the garage. It does not cost much more to add a last leaf if you require it later as opposed to having it on hand. Redoing the front and rear suspension with OME components is one of the best improvements I've made to the truck, I think you will be very pleased with the results-