STILLEN 504456 Stainless Steel Cat-Back Exhaust System - 11-13 M56 / 14-15 Q70 5.6L Near Cat-Back Exhaust System; 304 Stainless Steel Construction Polished Stainless Tips, End Pipes and Mufflers Increase of Horsepower and Torque Mild at Idle/Cruising - Aggressive Note Under Throttle; Limited Lifetime Warranty