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 Thats 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.