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Happy New Year!

6" B58 CATTED DOWNPIPE - 240i 340i 440i 540i 640i 740i

Original price $587.00 - Original price $587.00
Original price
$587.00
$587.00 - $587.00
Current price $587.00
  • 30 Day Money-Back Guarantee | IN STOCK


HIGHLIGHTS

• 6" 200 Cell High-Flow Catalyst
• Improved Exhaust Sound
• Faster Turbo Spool
• Stage 2+ Tune Compatibility

  

PROFILE


The ARM 6" B58 Catted Downpipe is perfect if you're looking for all of the performance of a Catless B58 Downpipe without the odor associated with increased emissions. Our B58 Catted Downpipe design incorporates a 6" high-flow 200 cell ceramic catalytic converter, making it a standout choice for those seeking power without while reducing emissions. The increased volume and improved turbo spool that from the catless variations are still present in our 6" B58 Catted Downpipe.

B58 6in Downpipe

The ARM 6" Catted B58 Downpipe replaces the restrictive factory downpipe with a 200 cell catalyst with a 6" diameter that significantly improves exhaust flow. This upgrade unlocks additional power and torque while reducing emissions compared to a full catless B58 downpipe, allowing you to safely run Stage 2+ tunes and enjoy a more vibrant sound from your B58-powered BMW.

ENHANCE THE SOUND OF YOUR B58

The ARM 6" B58 Catted Downpipe amplifies the overall volume of your B58's exhaust, bringing out the burbles and enhancing the audible presence of the turbo spool, even on the OEM tune.  Below is a sound clip of the ARM 6" Catless Downpipe, paired with our B58 Midpipe, and Single Exit Exhaust


CONSTRUCTION

The ARM 6" B58 Catted Downpipe starts with a 4.5" diameter precision CNC machined turbo V-band flange which matches up perfectly to the OEM turbo or upgraded turbo with an OEM flange.  It then rapidly transitions to the 6" OD high-flow catted section

B58 Downpipe



The ARM 6" B58 Catted 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 size 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

• ARM 6" B58 Downpipe
 

FITMENT GUIDE

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
BMW G30 540i B58 3.0L
BMW G30 540i xDrive B58 3.0L
BMW G32 640i B58 3.0L
BMW G32 640i xDrive B58 3.0L
BMW G12 740i B58 3.0L
BMW G12 740i xDrive B58 3.0L
BMW G15 840i B58 3.0L
BMW G15 840i xDrive B58 3.0L
TOYOTA A90 Supra B58 3.0L
TOYOTA A91 Supra B58 3.0L
 

ARM MOTORSPORTS LIFETIME WARRANTY

Every ARM Motorsports product is backed by a lifetime warranty which is automatically issued at the time of purchase. Your warranty protects you against any defects in craftsmanship or fitment. The warranty entitles you to a replacement unit.

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.
*Kits are made-to-order. As we do not physically keep everything in stock, kits have a ship time of about 3 weeks after your payment has processed. This is common for the N54 Single Turbo market if you look on other websites.

Unleash the full potential of your N54 engine with our Top Mount Single Turbo Kit, engineered for seamless fitment, durability, and big power capability. Designed to support 800whp+, this kit is the ultimate upgrade for those who demand power without compromise.

High-Quality 304 Stainless Steel Manifold

Crafted from 304 stainless steel, the manifold offers superior heat resistance, corrosion protection, and structural integrity. Unlike lower-grade materials, 304 stainless ensures long-term reliability under extreme heat and boost pressures, making it ideal for high-performance applications. The precision-engineered tubular design is optimized for maximum exhaust flow, reducing backpressure and enhancing turbo efficiency. This manifold is similar to ones being sold on AliExpress and other overseas markets. However, we've partnered directly with the manufacturer to provide these manifolds in the highest of quality. Unlike those that are drop-shipping similar manifolds from unreliable sources. You are purchasing directly from the source.

Industry-Leading Fitment

Fitment has been meticulously tested and compared against all major top-mount kits on the market, and ours ranks among the best. The compact yet efficient design ensures hassle-free installation, eliminating clearance issues that plague other kits.

Smart Wastegate Placement

No more tearing the entire kit apart just to make a simple wastegate adjustment. Our strategically placed wastegate design allows for quick, easy access, so you can fine-tune your setup without unnecessary downtime.

Built for Serious Power

With the ability to support 800whp+, this kit is designed for enthusiasts pushing their N54 to the limit. Whether you’re chasing high-speed pulls or dominating the track, this setup provides the boost response, reliability, and power potential you need.

So what's included? 

(x1) Top Mount T4 Manifold
(x1) Relocated Coolant Waterpipe 
(x2) Coolant Port Block Off Plugs
(1x) -4 Oil Feed Adapter
(1x) Rear Oil Drain Freeze Plug
(1x) 5/8" ID Oil Drain Hose
(1x) 5/8" Oil Drain Barb 
(x1) -4 Stainless Steel Oil Feed Hose + Adapter
(x16) OEM Exhaust Manifold Studs
(x16) OEM Reduced Length Exhaust Manifold Nuts
(x6) Elring Exhaust Manifold Gaskets
(1x) T4 Turbo Blanket
(x3) O-Rings
(1x) Turbo-To-Intercooler Piping
(x1) Turbo (Optional)
(x1) 3" V-Band Hood Exit (Optional)
(x1) 44mm Wastegate (Optional)