The Powerstop Rear Brake Discs you mentioned, specifically the "Evolution Drilled & Slotted Series," are aftermarket brake components designed to enhance the braking performance of a 2015-2023 Ford Mustang S550. These brake discs are a popular choice among automotive enthusiasts and are known for their improved braking efficiency and aesthetics. Here are some key features of the Powerstop Rear Brake Discs in the Evolution Drilled & Slotted Series: