aFe is proud to introduce the aFe Twisted Steel? Down-Pipe with a 300 CPSI high-flow catalytic converter for the 2012-2014 BMW F30 335i with the L6-3.0L (N55) engine. In testing this system resulted in a max gain of 10 horsepower and 16 lbs. x ft. of torque and outflowed the restricted OE catalytic converter by up to 150%. This high performance down-pipe delivers the perfect balance of pure, race-inspired performance, in-cabin driving comfort and the excitement of exhaust sound and tone during normal cruising or aggressive hard throttle. aFe also included a massive, lightweight, 4" diameter, 304 stainless steel tube with a 300 CPSI, high-flow catalytic converter. The catalytic converter is not only environmentally friendly it also prevents check engine lights. Twisted Steel 4 IN to 3 IN 304 Stainless Steel Street Series Down-Pipe w/ Cats BMW 335i (F30) 12-13 L6-3.0L (t) N55 4" DIA 304 Stainless Steel; 300 CPSI Stainless Steel High-Flow Catalytic Converter; Retains Factory O2 Sensors; 100% TIG-Welded; No modification necessary; Hassle-Free Installation; OE Style Brackets; OE Style Turbo Flange; Prevents Check Engine Light BMW 335i (F30) 12-13 L6-3.0L (t) N55