SKU: 23173764262

Active Autowerke Downpipe w/ AFlow Cat - 2016+ B58 Gen 1 & Gen 2

Sale price$765.00 Regular price$850.00
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Description

Active Autowerke Downpipe w/ AFlow Cat - 2016+ B58 Gen 1 & Gen 2Active Autowerke BMW B58 Catted Downpipe now includes turbo flange gasket NOTE: Fitment applies to US model cars only unless specifically stated. We cannot guarantee fitment to non US model cars. BMW introduced a new valvetronic, single turbo version of its direct injection engine for the later F Chassis models beginning in 2016 and carried over to the G chassis models. The Active Autowerke B58 downpipe for the M340i and M440i helps unleash some of

Active Autowerke BMW B58 Catted Downpipe - now includes turbo flange gasket

NOTE: Fitment applies to US model cars only unless specifically stated. We cannot guarantee fitment to non-US model cars.

BMW introduced a new valvetronic, single turbo version of its direct-injection engine for the later F-Chassis models beginning in 2016 and carried over to the G-chassis models. The Active Autowerke B58 downpipe for the M340i and M440i helps unleash some of the potential that is restricted by the OEM downpipe.

Turbochargers are powered by spent exhaust gases created during the combustion process. The quicker these gases are evacuated, the better. Unfortunately, the factory down pipe in the B58 is quite restrictive, which results in slower exhaust gases and slower turbo spool.

The Active Autowerke B58 Signature down pipe utilizes 4.5 diameter stainless steel piping in order to provide more power, quicker spool, and extreme durability. It then tapers down to 3.5" where we've incorporated a stainless flex joint and then down to 80mm to meet the OEM exhaust system. We never drop the diameter less than the stock diameter of 80mm. 

This variant includes a 4.5" Active Aflow catalytic converter that will NOT produce a CEL for cat efficiency guaranteed by Active Autowerke (full replacement within first two years of ownership).

The Active Aflow super high output catalytic converter features full 304 stainless steel construction, including the substrate. Active Aflow Catalytic Converters are EPA registered and compliant in 49 states and fully OBD2 compliant, perfect for use on 1996 and newer vehicles. Active's proprietary precious metal loading technology ensures greatly reduced emissions, eliminating most "Check Engine Lights" due to cat efficiency errors. These high flow catalytic converters outperform stock converters and provide a reliable solution to the most common catalytic converter problems.

The Active Aflow Catalytic Converters are rated for engines putting out up to 800 horsepower while maintaining a high flow capacity. The reduced back-pressure from this high flow catalytic converter will allow you to maximize your engines horsepower without the harmful emissions. Say goodbye to Check Engine Lights for cat efficiency and failed emissions tests!

Please Note: These catalytic converters are not legal for use on vehicles registered in the state of California as a result of California Vehicle Code Section 27156 and 38391.


NOTE: Federal law prohibits the tampering of an emissions control device. Mobile Source Enforcement Memorandum 1A, allows for aftermarket parts to be used in the repair or replacement of emissions control systems, provided the emissions aren't adversely affected. There is no mention or reference to cell density or converter volume dimension. The Active Aflow catalytic converter will produce emissions that will meet the standards set by the EPA, not CARB.

Features:

  • NO CEL for catalytic efficiency when using this downpipe

  • Active EPA registered high flow and fully OBD2 compliant

  • Casted upper stainless steel V-Band for precise fitment

  • 4.50" diameter piping allows for maximum power output

  • Quicker turbo spool

  • Rated for up to 800 hp applications 

  • Withstands up to 1500 F

  • Can reach operational efficiency within 9 seconds of startup

  • Easily bolts-on no cutting or welding required

  • Durable construction from TIG welded 304 stainless steel

  • Precise fitment

  • Ultra high flow 400 cell per square inch catalyst

  • EPA compliant for use on OBD2 vehicles (1996 and newer) except in California

  • 304 stainless steel substrate is furnace braised to the mantle for outstanding durability

  • Active proprietary precious metal loading technology ensures greatly reduced emissions

  • Ideal for Forced Induction Applications with no loss of HP

  • Both passengers and drivers are safe from harmful emissions and noise

  • Covered by 5 Year / 50,000 Mile Warranty (on shell and tube ends) and 2 year / 25,000 Mile Warranty on the Catalytic core to original purchaser only - NOTE: warranty will be null and void if your car has excessive burble (greater than stock) as that physically destroys the catalytic core

  • Made in Miami, Florida

Active Autowerke B58 Signature Downpipe Benefits

The speed of a turbo's impeller wheel is limited by exhaust back pressure. A larger down pipe relieves some of this pressure, resulting in quicker and more efficient spool. With Active Autowerke's Signature downpipe, your B58 can rev quicker, and deliver more horsepower and torque.

Minimizing back pressure while retaining daily drive-ability was the goal of our B58 downpipe. Owners can now upgrade to a product that is affordable, reliable, and easy to install.

After months of research and development, our engineers settled on a 4.5 diameter pipe which utilizes the least number of bends possible. The large volume helps the turbo spool as quickly as possible by eliminating back pressure during spool up. We are ushering in a new era in performance where we maintain air control standards without significant losses in power by using the Active super high output catalytic converter in our signature downpipe.

Constructed entirely from 304 stainless steel with 1.5MM wall thickness, we are confident that you'll be pleased with how robust and durable this down pipe is. Trouble-free installation and a long lifespan ensure that you'll enjoy many miles of performance with your B58!

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: 23173764262

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4.8 ★★★★★
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Verified Purchase
William Gordon
Omaha, US
★★★★★ 5
Good watch
Color: Black
Needed a practical watch for everyday use and this fit the bill. Not too big, has a good sized watch face.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on November 20, 2025
R
Verified Purchase
Ramo
West Palm Beach, US
★★★★★ 5
Nice looking, easy to read, comfortable silicone strap, hard to buckle.
Color: Black
This watch has all the features other Ironman watches have plus a 100 lap interval timer. The interval timer is possibly the reason this watch is slightly more expensive than the other IM variants with the same size and general appearance. I find this watch to be nicer looking when going out to dinner than the more common multi-colored IM watches, though most of the functions are available on the others. My previous Ironman watch had a resin strap, which was somewhate stiff when putting it on. It was comfortable enough wearing on the river, but later in the day I sometimes took it off for comfort. This watch has a soft, stretchy, more comfortable silicone strap, that, sadly, is hard to buckle and tuck-in.
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Reviewed in the United States on June 4, 2024
A
Verified Purchase
Amazon Customer
Houston, US
★★★★★ 2
Longtime Ironman Wearer -- I Hate This Watch
Color: Black
I've worn the old Ironman 100 Lap Watch for Years I would still be wearing those watches if the Indigo on them didn't consistently fail. My main requisite is large, easy to read digital display, and the ability to turn the Indiglo on 20 seconds a day once or twice to see time in dark. If I could have found a simple watch with a large display made by any other reputable manufacturer I would have bought it instead. I have truly come to dislike Timex because their Indiglo fails so consistently, on (5) different Ironman's I've owned. Doubt this one'll be any better, viewing it a disposable purchase after a year. Unsurprisingly, Timex is an American company, all marketing no quality, and yes I'm an American, looking at something Casio Seiko, Swiss or Japanese made. They get fundamentals right in terms of quality. The band on this is redesigned. Grippier. Tougher to adjust or put on, but more apt to stay on and not slide once on. I'm used to the old band, don't love or hate this new one. I will usually take my watch off while typing for a long time, not as easy to do with this, not a dealbreaker, can see the sense in making a swimming and exercise watchband a bit tougher. I hate the branding on this watch. Bright red Ironman logo on both ends of the band near the watch. Even worse is the Timex and Ironman words ATOP the glass on the watch. This means they throw shadows down onto the watch face below the glass. This effect gets even worse with the magnification underwater. Inexcusable design flaw, simply so some corporation can self-advertise its products. The combination of these two sets of branding make the watch look cheap, gaudy, and inappropriate for any remotely formal wearing. This would not have been the case if it was understated in color scheme. Without the two red marks on the band, and the absolutely moronic decision to place the branding on the watch glass, you have something understated you could get away wearing all the time. Not with the branding. There are also two lines running horizontally above and below the time. I hate these when I'm looking at it underwater. Haven't tried the lap functions yet, I usually open lake swim, maybe the lines help with that, but for my use I hate them. I'm 6'4" tall, people complain the watch is big, it feels to me if anything a bit undersized or the proper size, others may find it big. I would rather have a slightly larger size with bigger numbers. Biggest plus is time SUPER easy to read. I'd love to be able to turn date off and only have time display and nothing else in some mode. I don't need to check the date 6 times a day. Love to have mode where I press one button, upper left say, and date shows for five seconds or something. Indiglo about the same as old big Ironman 100, excellent--when it doesn't break which it almost always does. I have many of these watches where the time still shows but Indiglo never works, Timex themselves admitted to me this is a known problem. The rounder face, versus rectangular, better looks, but wonder if it is optimal way to make most readable. I would pass on this watch. I have always liked Ironman watches, but the branding is so bad, glass especially, and the absymal quality of Timex Indiglo, are unacceptable.
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Reviewed in the United States on May 9, 2023
S
Verified Purchase
SSM
New York, US
★★★★★ 3
Cool & functional
Color: Pink
Attractive watch. Simplistic, yet cannot understand everything without not having instructions. Watch did no come with instructions, which became hard to figure out all its functions.
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Reviewed in the United States on December 28, 2025
S
Verified Purchase
Shelton B.
Carnegie, US
★★★★★ 5
Great watch
Color: Black/Digital/Green
Love this watch. Comfortable. reliable. Not too fancy. Inconspicuous. And all for a great price.
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Reviewed in the United States on March 27, 2026

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