Does the AFlow Catted Downpipe for B58N need a tune?

No. Active Autowerke sells the AFlow Catted Downpipe for B58N BMW models as a no-tune part. With the converter rated to 950 horsepower, there is ample margin if the owner later adds a tune to make more of the extra flow.

Does it fit the 2025 M340i or M440i?

No. Active Autowerke states plainly that this downpipe is not for the 2025 and newer M340i and M440i, whose factory downpipe is built differently. Those cars take a separate Active Autowerke downpipe made specifically for the G20 and G22 models.

Will it set a check engine light?

Active Autowerke states that the AFlow converter will not set a catalyst efficiency code. The 400 cell converter reaches working efficiency within 9 seconds of a cold start, so the rear oxygen sensor reads a working catalyst almost straight away.

How does the AFlow version compare with the GESI version?

Both share the same 5 inch stainless pipework and 80mm outlet. The AFlow version uses an Active AFlow converter rated up to 950 horsepower. The GESI version uses a GESI G-Sport converter rated up to 1,000 horsepower and costs more.

Is installation difficult?

The downpipe bolts in without cutting or welding, locating at the turbo on a cast stainless V-band and meeting the factory exhaust at 80mm. A lift makes the job far more manageable, and because nothing is modified, the factory downpipe can be refitted later if needed.

Description

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Description

Active Autowerke AFlow Catted Downpipe for B58N BMW 5 to 7 Series, X3, X5 and X7 (2025 and Newer)

Active Autowerke’s AFlow Catted Downpipe for B58N BMW 5 to 7 Series, X3, X5 and X7 gives the 2025 and newer third-generation B58 a 5 inch stainless downpipe with a 5 inch Active AFlow converter, then narrows through a stainless flex joint to meet the stock 80mm exhaust. Active Autowerke builds it in Miami from 1.5mm wall 304 stainless, and the AFlow converter carries a 950 horsepower rating, far above what a factory B58N produces. That makes it the sensible pick for a 540i, 740i or X5 xDrive40i owner; the GESI Catted Downpipe for B58N costs more for a slightly higher rating.

Features

Active AFlow super high output converter with a 304 stainless substrate furnace brazed to the mantle
EPA registered, OBD2 compliant converter
Built not to set catalyst efficiency check engine lights
Cast stainless upper V-band at the turbo
Stainless flex joint ahead of the 80mm outlet
Supplied with a turbo flange gasket
TIG welded 304 stainless, made in Miami, Florida

Specifications

Main piping diameter: 5 in
Outlet diameter: 80mm
Wall thickness: 1.5mm
Converter diameter: 5 in
Catalyst cell density: 400 cpsi
Converter rating: Up to 950 hp
Temperature limit: 1500F

What’s Included

AFlow catted downpipe
Turbo flange gasket

Applications

BMW 540i: G60 | 2025-present | 3.0L B58N
BMW 640i: 2025-present | 3.0L B58N
BMW 740i: G70 | 2025-present | 3.0L B58N
BMW X3: G45 | 2025-present | 3.0L B58N
BMW X5 xDrive40i: G05 | 2025-present | 3.0L B58N
BMW X7 xDrive40i: G07 | 2025-present | 3.0L B58N

Notes

The AFlow Catted Downpipe for B58N does not fit the 2025 and newer M340i or M440i, which take the GESI Catted Downpipe for G20
B58 vehicles built through 2024 take the AFlow Catted Downpipe for B58
Fitment applies to US-model vehicles only; Active Autowerke cannot guarantee it on other market versions
Warranty is 5 years or 50,000 miles on the shell and 2 years or 25,000 miles on the catalytic core, original purchaser only, void on a vehicle tuned for more burble than stock

Frequently Asked Questions

Does the AFlow Catted Downpipe for B58N need a tune? No. Active Autowerke sells the AFlow Catted Downpipe for B58N BMW models as a no-tune part. With the converter rated to 950 horsepower, there is ample margin if the owner later adds a tune to make more of the extra flow.
Does it fit the 2025 M340i or M440i? No. Active Autowerke states plainly that this downpipe is not for the 2025 and newer M340i and M440i, whose factory downpipe is built differently. Those cars take a separate Active Autowerke downpipe made specifically for the G20 and G22 models.
Will it set a check engine light? Active Autowerke states that the AFlow converter will not set a catalyst efficiency code. The 400 cell converter reaches working efficiency within 9 seconds of a cold start, so the rear oxygen sensor reads a working catalyst almost straight away.
How does the AFlow version compare with the GESI version? Both share the same 5 inch stainless pipework and 80mm outlet. The AFlow version uses an Active AFlow converter rated up to 950 horsepower. The GESI version uses a GESI G-Sport converter rated up to 1,000 horsepower and costs more.
Is installation difficult? The downpipe bolts in without cutting or welding, locating at the turbo on a cast stainless V-band and meeting the factory exhaust at 80mm. A lift makes the job far more manageable, and because nothing is modified, the factory downpipe can be refitted later if needed.

About Active Autowerke

Active Autowerke was founded in Miami, Florida in 1981 by brothers Mike and Karl Hugh as a BMW service shop, and turned to performance in late 1995 when Karl, a University of Miami engineering graduate, led its first M3 and 325i turbo kits. Supercharger kits for the E36, E46 and E9X followed, and its Signature Equal Length mid-pipe is protected by US Patent 11248511 and European and UK Patent 3882441.

Additional Information

The Bulletproof Automotive website contains many thousands of products purchased in multiple different currencies. All of the prices are entered manually and accurately at the time of entry. Due to the consistently fluctuating international exchange rates, at times prices may not be able to be honored at their original intended rate. We apologize for any inconvenience this may cause, unfortunately our website is unable to compensate dynamically for what can at times be volatile changes in the cost of items due to currency values fluctuating, changes in prices from suppliers, changes in shipping and import duties, and other factors. Rest assured that any order you place on line will be at zero risk to you in this area. If in the event your order cannot be fulfilled at the original intended website price we will offer you a 100% refund, no questions asked. We will continue to do our best to maintain updated prices and we will always continue to offer our price match guarantees as well to ensure our prices are always the best for you. In short, prices may change without notice. It is always advised to give us a call prior to placing your order online to confirm availability and to confirm current pricing.

Shipping Policy

Items that are in stock in the US, either at Bulletproof’s warehouse or at a supplier’s warehouse, are generally delivered within 7-10 days. Special order items from overseas take considerably longer. As a courtesy Bulletproof offers delivery estimates to our customers which take into consideration manufacturer availability and shipping schedule. These estimates represent our best guess based on previous orders from the manufacturer and do not in any way imply a guaranteed delivery window. Many manufacturers work in a “just in time” inventory system and often take 2-20+ weeks to produce an item once an order is submitted. All deliverable items are then sent to our Japanese warehouse. Bulletproof ships a minimum of one full ocean freight container every month from Japan, oftentimes more than one a month. Ocean freight takes an average of 4 weeks. Typically it breaks down to one week in Japan for paperwork and customs, two weeks by boat and one week in US customs/clearance. Due to the wide number of variables between manufacturer and shipping schedules, delivery estimates are simply just that – estimates. We attempt to estimate conservatively and we usually deliver faster than our estimates suggest. It is not Bulletproof’s policy to guarantee delivery time of any special order item, this is impossible for us to do. By ordering you acknowledge that there is no required delivery ETA and an order may not be canceled or altered due to manufacturing or shipping delays, all ETA’s are provided as a best guess only. Please review the full Terms & Conditions here.

BP Pricing Difference

We do pricing a little differently on our JDM brands and we believe in making things simple and clear. No hidden fees or surcharges. Every price you see includes the shipping cost to our office in Los Angeles, California and all the associated taxes/duties/fees for bringing the products into the US. The only shipping you ever pay is from our facility in the US to your location. Be wary of resellers that don’t include the cost of international shipping in their pricing on JDM parts. While we believe we’ll always have the lowest all-in price on JDM products, we offer a price match guarantee for all authentic parts purchased from authorized dealers as well. For many international customers, it’s much more affordable to ship from the USA than from Japan directly, as the air freight and ocean freight costs are typically much less. However, for customers looking to ship directly from Japan outside of North America, or domestically in Japan, we can provide pricing specifically for that scenario. Please do not hesitate to contact us with any pricing questions or concerns. Please email us at sales@bulletproofautomotive.com with any inquiries.

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Active Autowerke AFlow Catted Downpipe for B58N BMW 5 to 7 Series, X3, X5 and X7 (2025 and Newer)

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Active Autowerke AFlow Catted Downpipe for B58N BMW 5 to 7 Series, X3, X5 and X7 (2025 and Newer)

Features

Specifications

What’s Included

Applications

Notes

Frequently Asked Questions

About Active Autowerke

Reviews