Add power, sound and unique style to your BMW X5X6 M with this cat - back system which produced gains of up to 20 horsepower and 33 lbs. x ft. torque as measured on our in - house dyno. Dual 3 to 2 - 12 mandrel - bent, brush finished 304 stainless steel tubing keeps exhaust flowing smoothly for power gains you can feel. Designed with a transverse, high flow muffler finished in high temp powder coating for long lasting good looks and unique sound. The factory exhaust valve motor is used to regulate the exhaust flow from a closed - valve, sporty tone to wide - open, aggressive, performance sound.