2012-21 BMW F-Chassis M135i M2 M235i 335i 435i Catless Downpipe

Restrictions in the exhaust system rob horsepower and torque especially on turbocharged cars. Thus, removing as many exhaust flow restrictions will increase horsepower and torque significantly. The factory catalytic converter found in the factory downpipe is a big culprit of this and is a major exhaust flow restriction. The factory catalytic converter is made up of catalyst material formed into "honeycomb" weaves. Exhaust gas must pass through these tiny "honeycomb" weaves on its way to the exhaust system thus causing a major exhaust flow restriction. It also causes turbulence after the catalytic converter which causes the exhaust flow to slow down (which increases restriction).  By replacing the factory downpipe / catalytic converter with our Extreme Online Store Competition Series 4" Race Cat Downpipe, more power is unleashed and You will feel the difference instantly. 

Our Competition Series Race Cat Downpipes is constructed out of 100% 304-grade stainless steel and utilizes mandrel bent piping. They are 100% TIG welded by our in-house fabricators and built in the USA. The factory turbocharger turbine housing utilizes a V-Band flange which we have duplicated and CNC machined cut out of billet 304 stainless steel.  Stainless Steel CNC machined O2 sensor and laser cut brackets are TIG welded using stainless steel rods. The O2 sensor is positioned at the factory location. Since the outlet of the turbocharger is 3.5" and the factory exhaust system is 3", the factory downpipes reduce size using short transitions from 3.5" before the catalytic convert and 3" afterward. Due to the space needed for the catalytic converter, the factory downpipes reduce in size using very short transitions. Since our Race Cat downpipes delete the catalytic converter, we have more space. Thus, we use very long transitions.  These longer transitions allow the exhaust gas time to smoothly transition from the larger piping to the smaller. Also, since we utilize a larger 4" pipe right after the turbocharger, turbo back pressure is significantly reduced. This results in less exhaust turbulence and backpressure which again improves throttle response and increases turbocharger spool times (less turbocharger lag). 

Features:

• Higher Max Horsepower Power Curve
• Higher Initial Torque Curve - The torque curve hits faster and higher and longer
• Better throttle response and faster turbo spool-up times
• Mandrel Bent 4" piping With Smooth transition to the exhaust system
• 100% Stainless Steel Construction
• 100% TIG welded for better quality welds
• Precision CNC machined turbocharger V-Band flange
• Compatible with the factory or aftermarket exhaust systems
• Track tested durability With Limited Lifetime Warranty
• Expected gains of 20whp and 30wtq when used with a Stage 2 Tune