Evolution Racewerks 4″ Downpipe for BMW N26 Engine – 125i/228i/320i/328i/428i

CAUTION: This product is intended for OFF ROAD COMPETITION USE ONLY. Not legal for use on pollution controlled vehicles upon public road/highways. THIS PRODUCT IS FOR SALE FOR ALL 49 STATES EXCLUDING CALIFORNIA.  In addition to vehicle use verification, a Vehicle Compliance Waiver needs to be signed.

THIS ITEM IS NOT FOR SALE, INSTALLATION, OR USE ON LICENSED VEHILES IN THE STATE OF CALIFORNIA. 

The item is for sale for international customers without restriction.

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 Sports Series 4" High Flow Catted Downpipe, more power is unleashed!

The factory catalyter uses a 400 cell ceramic core.  What the 400 cells means is that per every inch, there are 400 "cells" that the exhaust gas must pass through.  We use a 200 cell metallic core.  By having less cells per square inch, these individual "cells" are bigger in size thus allowing exhaust gas to pass through it more easier.  Thus, the lower the cell count, the higher the flow.  Higher flow = more power, faster turbo spool up (less turbocharger lag) and better throttle response.  Bottom line, faster.  The benefits of a metallic catalytic converter vs a ceramic like the factory is that it can take more heat and is more durable (last longer).  They are also lighter than their ceramic counterparts.

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.

One of the main features of our N26 downpipe is the CNC machined solid stainless steel billet ball joint.  The factory downpipe uses a press formed process to produce the "ball" joint to connect to the factory exhaust.  This process can be done very inexpensively when done in large productions runs.  Unfortunately, the drawback of this press formed "ball" joint is that the interior of the pipe also mimics the outside.  When exhaust flows through a pipe, the majority of the exhaust flow tends to stay on the outer edges of the pipe.  Thus, when exhaust flows into the "ball" section, it goes into the valley created by the "ball" joint and then back up the other side.  This creates tremendous amounts of turbulence in the exhaust flow right at that section.  Turbulence in turn, slows down exhaust flow velocities as well as increase back-pressure.  It's a well known fact that with turbocharged cars, you want the least amount of back-pressure while still maintaining high exhaust flow velocities.  Why?  Because low back-pressure and high velocities allow the turbocharger to spin faster.  This equates to reducing turbocharger lag and faster spool times.  Throttle response is also improved.  We had originally thought to use the same press form process to manufacture our downpipes.  However, very quickly we noticed this flaw to the process and decided to CNC a solid stainless steel billet "ball" joint.  This allowed us to keep the factory connection while keeping the interior of the ball smooth.  This allows the exhaust to flow unrestricted through the "ball" joint.  While this CNC solid stainless steel billet was very expensive to manufacturer, our motto at ER is "Performance, no compromises".  Our in house testing showed that we did indeed have real world improvements with this new CNC billet "ball" joint and thus worth the extra costs.  This is why the N26 downpipes do cost a little bit more than the N20 downpipes as the N20 downpipes do not have the ball joint system but use a traditional slip-fit design which is cheaper for us to manufacturer.  The pictures below show the factory "ball" joint cut in half (to show in the interior) versus our CNC solid stainless steel billet "ball" joint.

Since we are able to reproduce the factory "ball" joint v-band connector, our downpipes are designed to fit perfectly with either the factory exhaust system or your aftermarket exhaust system.  There are no compatibility issues whatsoever.  The downpipes will come by default with brushed finish.

OPTIONS

Ceramic Thermal Coating - The purpose of ceramic coating downpipes is to keep heat from the exhaust gases inside the downpipe from radiating out.  This keeps underhood temperatures lower and less heat absorption by nearby parts/surfaces.  Another added benefit is that by keeping in heat (energy) in the exhaust gases inside the downpipe, exhaust flow velocities stay up, resulting in lower backpressure.  The ceramic coating also adds additional corrosion resistance.  We utilize the best ceramic coating possible.  Our thermal coating can resist up to 2000F of heat.  It is available in black only (all the other colors cannot withstand heat that high).

Additional O2 Sensor Bung -  An additional O2 sensor bung can be added so that you can easily add a wideband o2 sensor and gauges so that you can monitor air/fuel ratios.  The additional O2 sensor bung will come pre-installed with a plug so that you do not need to run the o2 sensor right away.

Optional EGT (Exhaust Gas Temperature) Bung - An additional 1/8" NPT bung can be added so that you can easily add a EGT sensor and gauge.  The optional EGT sensor bung will come pre-installed with a plug so that you do not need to run the EGT sensor right away.