The rear strut tower bar helps the rear, the same way the front strut bar helps the front of the car.
Carbon Fiber rear strut tower bars are incredibly lightweight, this bar uses a thick 40mm carbon fiber shaft and lightweight end plates for the ultimate in rigidity and weight savings.
For the Sedan and Coupe models, the bar runs through the trunk space right behind the rear seats and a few inches below the rear deck lid. For the Wagons and Outback Sport, the bar runs across the rear cargo area directly behind the rear seats. Simply remove the two bolts that hold the bar in place if you never need to temporarily reclaim the extra trunk/cargo space.