ARM Motorsports B58 DOWNPIPE - 240i 340i 440i

In stock
Regular price $297.00
Quality Content


• Increase Power and Torque
• Faster Turbo Spool
• Improved Exhaust Sound
• Safely Flash Stage 2+ Tunes
• SS304 Stainless Steel


The ARM 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 your downpipe unlocks power, improves turbo spool, allows you to safely run stage 2+ tuning, all while increasing the sound of your B58-powered BMW.   


The ARM B58 Downpipe will increase the overall volume of your BMW, open up the exhaust burbles even on OEM programming, and make the turbo spool significantly more audible.  The M240i in the video below is only equipped with the ARM B58 Downpipe, it is otherwise on a 100% stock exhaust.  The car has never been flashed, it is on the original DME programming from BMW.  


The ARM B58 Downpipe is built with SS304 stainless steel and backed by the ARM Motorsports Lifetime Warranty.  The ARM B58 Downpipe starts with a 4.5" diameter precision CNC machined turbo v-band flange

B58 Downpipe

The ARM B58 Downpipe then gradually reduces to a 3.1" diameter before the flex section.  The flex section is incorporated into the ARM B58 Downpipe to relieve stress on the turbo during aggressive driving.

B58 Downpipe

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

B58 Downpipe

The 3.1" diameter continues after the flex section to allow for an easy installation to the OEM midpipe, or any midpipe that connects to the OEM B58 downpipe.    

The ARM B58 Downpipe features two O2 sensor bungs to allow for reinstallation of the OEM oxygen sensors.  The O2 sensor bungs are located closer to the turbo on the ARM downpipe to avoid stretching the O2 sensor wires during installation.  A tune or CEL Delete will be required to avoid a check engine light from displaying on instrument panel.

B58 Downpipe


• ARM B58 Downpipe


Make Model Submodel Engine
BMW F22 M240i B58 3.0L
BMW F22 M240i xDrive B58 3.0L
BMW F23 M240i B58 3.0L
BMW F23 M240i xDrive B58 3.0L
BMW F30 340i B58 3.0L
BMW F30 340i xDrive B58 3.0L
BMW F32 440i B58 3.0L
BMW F32 440i xDrive B58 3.0L
BMW F33 440i B58 3.0L
BMW F33 440i xDrive B58 3.0L
BMW F34 340i xDrive B58 3.0L
BMW F36 440i B58 3.0L
BMW F36 440i xDrive B58 3.0L

This product is for Off-Road Use Only. Items sold for off-road use only are illegal to use on public roads in most states and provinces. This product is intended for racing vehicles which may never be used on a public road.