The are many different pieces of the puzzle when it comes to getting the power to the ground. One of those pieces is not allowing the driveline to "deflect" during acceleration. As the engine revs, it puts stress on all the driveline components as the power makes it way to your rear wheels. One of the weaker points of the 86 chassis is the rear subframe bushins and the differential mounts.
Cusco has developed this differential brace to prohibit unwanted deflection. This allows the power to get to where you want it to go easier and better.
This is a great addition to any 86 owners vehicle!