Sorry to hear about this, I have the same leveling kit and rides really smooth. Although I do have the stock tires right now.
My truck has those stupid ContiEcoPlus sh*t tires. The sidewall has zero flex but on the hwy/IS they are really smooth. SF/Bay area, CA has some of the sh*tty a$$ streets. Every time i drive over a crack, it feels like a drove over a gorge.