A sway bar doesn't give traction. It only takes it away from that end. The reason many setup sheets have them is because they are running a huge spring imbalance front to rear with the front wheel rate much higher than the rear. The sway bar is a bandaid for this imbalance. If you are running a rear sway bar and the back end is washing out, remove it. If it works, it doesn't mean the rest of the setup isn't off though.