BMW N20 Downpipe Install Guide

Thank you for purchasing the ARM N20 Downpipe! In this guide we will walk you through how to properly install your N20 Downpipe.


Installing the ARM Motorsports BMW N20 Downpipe will improve airflow by reducing restrictions caused by the catalytic converter.


EASY! This downpipe can be installed within 45-90 minutes with basic tools.




Step 1) Take off engine cover and unlatch release tabs on O2 Sensor connectors from wires.

Step 2) Using an 8,10,and 13MM sockets remove all bolts securing the underbody plastic panels.

Step 3) Work the O2 sensor wires down toward the ground, and disconnect any clips holding the harness in place as you do so.

Step 4) Loosen the nut that holds the clamp of the midpipe to the downpipe. (13MM)

Step 5) From the top of the engine, remove the bolt on the clamp from the turbo to the downpipe. (13MM)

Step 6) Remove the two mounting bracket bolts. (13MM)

Step 7) Pull downpipe away from bracket bolts and rotate to ease the Downpipe away from the vehicle. Make sure that the wires do not get in the way or get pulled on.

Step 8) Remove the O2 sensors from the original downpipe, notate which sensor is pre, and post-cat.

Step 9) Place the O2 sensors on your ARM downpipe and torque to 37 ft-lbs.

Step 10) Slip the downpipe into the midpipe. It is best practice to have a pipe expander on hand just incase the midpipe needs to be expanded. You can rent this for free at your local auto parts store.

Step 11) Place the V band clamp around the downpipe and turbo flange. Leave the bolts loose.

Step 12) Go to the clamp on the turbo and tighten down to 24 ft-lbs. (13MM)

Step 13) Tighten down the bolt on the clamp at the midpipe to 16 ft-lbs. (13MM)

Step 14) Rework the O2 sensor wires back up to the top of the engine bay to plug back in. Make sure to clip any mounting locations back in place.

Step 15) Reinstall engine cover and underbody parts. (8,10,and 13MM)


Now just like that, you have installed your N20 downpipe! You will now feel your N20 awaken! With increased exhaust notes, and acceleration due to quicker spooling, you will enjoy the new found power of your N20 vehicle.

Should you have anymore questions, please feel free to reach out to us at 

Thank you for reading!

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