Performance Mid Pipes: The Performance Mid Pipes replace the factory mid section with a 3” stainless steel X-pipe, mating to the factory Axle Back.Important fitment notes: Pairing AWE's Performance Mid Pipes to the factory exhaust will require cutting the factory mid pipe. Upgrading options: Equipping the Performance Mid Pipes or an Axle Back with intentions to add another section later? That’s a good thing. We've engineered the AWE Exhaust Suite for the M5 as a completely modular configuration that allows you to do just that, at any time. Simply add the desired configuration to your cart, and roar away.