aFe Power # 48-36315-HC is a Twisted Steel Down-Pipe, Street Series that fits 2016-17 BMW M2 (F87) L6-3.0L (t) N55 (more applications listed below pic available via Marken Performance). This down pipe has a unique 3-1/2" to 3" stepped design that is used to increase exhaust velocity and increase usable torque. It is constructed of mandrel-bent, brushed 304 stainless steel tubing for maximum performance, corrosion resistance and strength eliminating cracking. There is a 400 CPSI (cell per square inch) catalytic converter for maximum flow.
Part # 48-36315-HN is for race use only as it has no cat.
Part # 49-36330-C is a 3” Down-Pipe Back, MACH Force-Xp Series which is a great complement for the above down pipe that fits the 2016-17 BMW M2 (F87) L6-3.0L (t) N55. It is constructed from 100% hand TIG-welded, 3" to 2-1/2" mandrel bent, brushed finished 304 stainless steel tubing. A free-flowing, transverse high-temp powder-coated black finish is used to absorb high pitch tones producing a powerful sound and unleashing all available horsepower and torque. It has 4 quad light weight, 4” diameter, pure carbon fiber tips. This down-pipe back exhaust system incorporates a factory style exhaust valve which uses the factory exhaust valve motor (not included). The valve helps regulate, direct and control the flow of exhaust gases by opening, closing, or partially obstructing passageways depending on throttle position for maximum performance.