The Akrapovic Evolution and Slip-On line exhaust systems can be further enhanced with an optional hand-crafted carbon-fiber rear diffuser. Developed by Akrapovic’s R&D Department, this stunning diffuser, crafted from materials developed through Akrapovic’s racing involvement, is designed to perfectly fit the lines of the unique tailpipes of the Slip-On or Evolution systems, as well as complement the sleek and sporty shape of the BMW.