SKU: 14271227393

6 Inch B58 Downpipe for Supra 3.0T & BMW M240i, M340i, 340i, 440i, M440i, 540i, 640i, 740i, 840i, X5, Z4

Sale price$147.15 Regular price$163.50
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Ships within 48 hours · Estimated delivery Aug 10 - Aug 15

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Description

6 Inch B58 Downpipe for Supra 3.0T & BMW M240i, M340i, 340i, 440i, M440i, 540i, 640i, 740i, 840i, X5, Z4The 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. The ARM

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.

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.

If You are interested in 5" B58 Downpipe then look here

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.

Highlights

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

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. 

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.

Fitment

  • 2019+ G20, G22 & G26 BMW M340i & M440i & xDrive
  • 2019+ F22 BMW M240i & xDrive
  • 2021+ G42 BMW M240i & xDrive
  • 2019+ G05 BMW X5 40i & xDrive
  • 2019+ G29 BMW Z4 M40i
  • 2019+ G14/G15/G16 840i & xDrive
  • 2019+ G14/G15/G16 840i & xDrive
  • 2016+ F22/F23 BMW M240i & M240i xDrive
  • 2016+ F30/F31 BMW 340i & 340i xDrive
  • 2016+ F32/F33/F36 BMW 440i & 440i xDrive
  • 2016+ G30 BMW 540i & 540i xDrive
  • 2016+ G32 GT BMW 640i & 640i xDrive
  • 2016+ G11/G12 BMW 740i & 740i xDrive
  • 2020+ Supra A90/A91 3.0T

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.

Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
  1. Standard Shipping : 3-10 business days
  • If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
  • Please click here for more details>>> Return & Exchange Policy
SKU: 14271227393

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Verified Purchase
Kindle Customer
Bozeman, US
★★★★★ 5
Soft and cool.
Color: Cooling Blue Cover, Size: Queen (Pack of 2)
Love this pillow set. Comfortable addition and nice and cool at all times. Going to be great for when the hot weather hits
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on June 8, 2026
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Verified Purchase
Anna T
Waukegan, US
★★★★★ 5
As advertised for once! Lol
Color: Cooling Blue Cover, Size: Queen (Pack of 2), Color: Cooling Blue Cover, Size: Queen (Pack of 2)
Queen size set of 2 pillows, I'm giving it 5stars first bc it has a good length and width!! If you've ever bought memory foam pillows before you know some are small!! Anyways after having it for 5nights, we loved that me and my huddy could adjust the Thickness amount we had in it to our needs, me needing a thick pillow and my husband needing a flatter one. So this was perfect for that. So far its nice to sleep on, stays cool, doesnt get hot. I would say its on the frimer side but softer the more foam you take out! Really its just good for the amount you spend!! Will it last 10years probably not but what does now a days. This is the only time my huddy n I bought the same pillow and both love it so I'm just still in shock it worked out so well!!
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 28, 2026
L
Verified Purchase
Lana Cannon
Lowell, US
★★★★★ 5
Adjustable pillows
Color: Cooling Blue Cover, Size: Queen (Pack of 2)
I love these because they don't go flat. You can pull out whatever you need to make them comfy for you. They come in two different layers. So you have that protective cover over the main case that holds the memory foam. They're amazing to sleep on. I have had these last for years without going flat. If you hate flat pillows this is the way to go. They are very easy to wash. You just have to separate layers. They are very thick, you can adjust the thickness. Everyone in my house has at least one. They are worth the money. I have never had to replace them, because they went flat.
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Reviewed in the United States on May 6, 2026
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Verified Purchase
A
Charlottesville, US
★★★★★ 4
Good pillows
Color: Cooling Blue Cover, Size: Queen (Pack of 2)
Takes some getting used to but and the cooling doesn’t last very long in my opinion, but overall amazing comfy pillows. The materials are good and are washable. I mostly stopped waking up with a stiff neck and back.
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Reviewed in the United States on April 20, 2026
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Verified Purchase
Jonathan
San Leandro, US
★★★★★ 5
Believe the Reviews
Color: Cooling Blue Cover, Size: King (Pack of 2)
I purchased these pillows because we were in need of new pillows, I previously had allswell pillows which were from walmart and they were good to start but now they tragically became very sparse and it started to effect my sleep so I saw these after careful review on other pillows and reviews I came across these and I saw some reviews and videos and I ordered them.. first they are king size we ordered they are perfect for the bed, they are plump and soft, they are memory foam which has always worked out for me for support and kept it’s shape these are great it did have a little smell I guess from packaging but other than that they are a huge upgrade from what we had before! I’m excited because they are cooling too! for the price point can’t beat it and this is coming from someone who was about to spend money on a purple pillow this will be good for now definitely buy it.
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Reviewed in the United States on March 28, 2026

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