Sentra NISMO Sway Bars

Nissan advertises that the SE-R comes with a rear sway bar.......NOT.....its a piece of steel tubing under the solid axle not attached to the body like a Normal Sway Bar. Anyway, I purchased, but have not put on the NISMO rear sway bar yet. What should I expect...or should I have replaced both? There is also a front bar available. Anybody know anyone who has just added the rear bar and what were the results. Thanks