Redoing all the rubber suspension bushings in the car is a start. Replace them with rubber for a smoother ride, Urethane if you looking for a stiffer ride. Since you've already selected shocks and springs the above suggestion would be the only other thing I could recommend. You could also consider foam injection into the body. ITW Foamseal goes for about $150 for 5 cans and is pretty good stuff. It'll quiet the car down a bit and ad better rigidity from front to the rear discp