2011-UP BMW N20 F10 F25 E84 E89 Turbo Competition Series 4" Catless Downpipe
BM-EXH008 / BM-EXH013 ** Please provide us with your VIN to confirm fitment
Competition Series 4" Downpipes for your N20 four cylinder turbo engine! Fits all 2011+ 528i, 2011+ X1 s/xDrive20i, 2012+ X3 xDrive20i/xDrive28i or 2011+ Z4 sDrive28i
SHOWN WITH BRUSH FINISH
IMPORTANT: THIS ITEM IS INTENDED FOR RACE OR COMPETITION USE ONLY
Restrictions in the exhaust system robs horsepower and torque especially on turbocharged cars. Thus, removing as much 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 their 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 Competition Series 4" Catless Downpipe, more power is unleashed! Our dyno testing has shown around 14-16whp average peak gains and upwards of 24wtq peak gains! While peak horsepower is nice to look at on dyno charts, what's more important is the power curve. If you look at the dyno charts, torque hits MUCH earlier and harder. The torque curve is BROADER throughout the RPM band. More usable power. You have more time spent in the RPM band with higher horsepower and torque. This equates to faster turbo spool up (less turbocharger lag) and better throttle response. Bottom line, faster. You will feel the difference instantly.
Our Competition Series Catless Downpipes is constructed out of 100% 304 grade stainless steel and utilize 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 4" 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 4" and the factory exhaust system is 2.5", the factory downpipes reduces size using short transitions from 4" before the catalytic convert and 2.5" afterwards. Due to space needed for the cataylic converter, the factory downpipes reduce in size using very short transitions. Since our catless downpipes delete the cataylic 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. This results in less exhaust turbulence and backpressure which again improves throttle response and increase turbocharger spool times (less turbocharger lag).
The factory downpipe utilizes a flex bellow section that allows the exhaust system to move. This eliminates undue stress on the exhaust components like the exhaust system, downpipe, turbocharger and exhaust manifold. Many of our competitors do not feel it is important to keep this. While you do not see any adverse affects right away, over time, the stresses caused by not having a flex section and having a rigid exhaust system will cause premature wear and tear. Any stress failures like cracks will form quicker than usual on exhaust manifolds and exhaust components. Also, without a flex section, the exhaust system cannot properly deflect impact. Especially on lowered cars, whenever the exhaust system contacts the ground, the entire system gets pushed up. Without a flex, you can imagine how much stress is put into exhaust components like the exhaust manifold when the exhaust is pushed upwards. We fully understand that durability of our products is important. Thus, like BMW, we incorporate a flex section into our downpipe. Our flex sections are 100% stainless steel (cheap flex sections only have stainless steel center braids and steel caps) to ensure corrosion resistance.
We also retain the exhaust hanger like the factory downpipes to help support the weight of the exhaust system.