aFe 49-36306 Mach Force XP CAT Back Exhaust System for BMW 335i 2011 L6-3.0L Produces 11 horsepower, 13 pounds by feet of torque Constructed from 2.75 inch mandrel bent and high polished 304 stainless steel Also includes dual high flow resonators and dual 3.5 inch polished 304 stainless steel tips and mufflers The exhaust system is performance tuned Constructed to be corrosion resistant