ARM - B58 6" Catless Downpipe - 240i/340i/440i/540i/640i/740i

PROFILE

The ARM 6" B58 Downpipe takes the title of being the largest catless downpipe available for the B58 platform!  The sound coming from your B58 with the 6" section of the ARM B58 Downpipe will astonish you.  Even deeper tones, even better sound, and improved turbo spool.  

The ARM 6" B58 Downpipe is one of the foundational upgrades for giving your B58-powered BMW more power, torque, and sound.  The stock B58 downpipe comes from the factory with a catalyst that severely restricts exhaust flow, causing excessive backpressure with increased boost.  Upgrading to the ARM 6" B58 Downpipe unlocks power, improves turbo spool, allows you to safely run stage 2+ tuning, all while improving the sound of your B58-powered BMW.   

ENHANCE THE SOUND OF YOUR B58

CONSTRUCTION

The ARM 6" B58 Downpipe is built with SS304 stainless steel and is TIG welded.  The ARM 6" B58 Downpipe starts with a 4.5" diameter precision CNC machined turbo V-band flange which rapidly transitions to the 6" OD high-flow section.

The ARM 6" B58 Downpipe features two O2 sensor bungs to allow for reinstallation of the OEM oxygen sensors.  The pre-catalyst O2 sensor bung is located closer to the turbo on the ARM 6" B58 Downpipe to avoid stretching the O2 sensor wires during installation.  The post-catalyst O2 sensor bung comes with a built-in extension to allow the sensor to reach around the 6" section of the downpipe.  

The ARM 6" B58 Downpipe then reduces to the OEM 3.1" diameter to allow it to connect to the OEM midpipe or the ARM B58 Midpipe Upgrade.  The flex section is incorporated into the ARM 6" B58 Downpipe to relieve stress on the turbo during aggressive driving.

The ARM 6" B58 Downpipe is further secured by the 2-bolt bracket which utilizes the OEM downpipe mounting points.

IN THE BOX

FITMENT GUIDE