I made the mistake of adding a stiffer rear sway bar in the rear of a Grand Cherokee WJ for towing only to find out later that with an Equal-i-zer brand hitch the sway bar adds nothing. I know this because My WJ had JKS sway bar disconnects front and rear. Once after some offroading with the sway bars disconnected on both ends I wanted to move the trailer to a different area. I forgot about the sway bars being disconnected hitched up the trailer and drove about 100 miles before I remembered. Actually with the Equal-i-zer hitch connected you couldn't tell because the two spring bars on the Equal-i-zer stabilize side to side motion so well the Jeep couldn't rock side to side if it wanted to.
I also found out that adding a stiffer rear sway bar without adding a matching stiffer front sway bar increases oversteer on slippery surfaces. I finally removed it for that reason, the factory knew what they were doing when they sized the sway bar balance.