Active Autowerke AFlow Catted Downpipe - BMW B58N M340i / M440i (2025+)
Ships from the brand or distributor, usually in 3–7 business days
Make sure this fits your car
Fits: 2025+ BMW M340i (G20) and M440i (G22) with the B58N engine
For off-road / competition use only. Not legal for use on public roads in the United States, including California.
- Shipping at real carrier rates
- 30-day returns on unused parts
- Fitment help before you buy
On 2025 and newer M340i and M440i models, the B58N Gen-3 engine's factory downpipe includes a gasoline particulate filter and restricts flow. Active Autowerke's AFlow catted downpipe takes its place to help exhaust clear the turbo more quickly.
What you get
- Catted downpipe for the B58N Gen-3.
- Active's own AFlow catalytic converter.
- Replaces the factory GPF downpipe.
- No performance tune needed, according to Active Autowerke.
Good to know
- Expect 9 to 10 hours of labor to remove the stock GPF downpipe, since the subframe must come down.
- Fitment applies to US-model cars. Non-US fitment isn't guaranteed.
For off-road / competition use only. Not legal for use on public roads in the United States, including California.
2025+ BMW M340i (G20) and M440i (G22) with the B58N engine
| Model | Chassis | Years | Engine | Fits |
|---|---|---|---|---|
| M140i | F20/F21 | 2016–2019 | Gen 1 B58 | |
| M240i | F22/F23 | 2016–2021 | Gen 1 B58 | |
| 340i | F30/F31/F34 | 2016–2019 | Gen 1 B58 | |
| 440i | F32/F33/F36 | 2017–2020 | Gen 1 B58 | |
| 540i | G30/G31 | 2017–2019 | Gen 1 B58 | |
| 740i | G11/G12 | 2016–2019 | Gen 1 B58 | |
| X3 M40i | G01 | 2018–2019 | Gen 1 B58 | |
| X4 M40i | G02 | 2019 | Gen 1 B58 | |
| 640i GT | G32 | 2018–2019 | Gen 1 B58 | |
| M340i | G20/G21 | 2019–2024 | Gen 2 B58 (TU) | |
| M440i | G22/G23/G26 | 2021–2024 | Gen 2 B58 (TU) | |
| M240i | G42 | 2022–2024 | Gen 2 B58 (TU) | |
| Z4 M40i | G29 | 2019+ | Gen 2 B58 (TU) | |
| GR Supra 3.0 | A90/A91 | 2020+ | Gen 2 B58 (TU) | |
| 540i | G30/G31 | 2020–2023 | Gen 2 B58 (TU) | |
| 740i | G11/G12 | 2020–2022 | Gen 2 B58 (TU) | |
| X3 M40i | G01 | 2020+ | Gen 2 B58 (TU) | |
| X4 M40i | G02 | 2020+ | Gen 2 B58 (TU) | |
| X5 xDrive40i | G05 | 2019–2023 | Gen 2 B58 (TU) | |
| X6 xDrive40i | G06 | 2020–2023 | Gen 2 B58 (TU) | |
| X7 xDrive40i | G07 | 2019–2022 | Gen 2 B58 (TU) | |
| 840i | G14/G15/G16 | 2019+ | Gen 2 B58 (TU) | |
| INEOS Grenadier | Station Wagon/Quartermaster | 2023+ | Gen 2 B58 (TU) | |
| M340i | G20/G21 | 2025+ | Gen 3 B58 (48V) | |
| M440i | G22/G23/G26 | 2025+ | Gen 3 B58 (48V) | |
| M240i | G42 | 2025+ | Gen 3 B58 (48V) |
Not sure? Email sales@b58racing.com with your VIN.
- Ships from the brand or distributor, usually in 3–7 business days.
- Shipping is charged at the carrier's rate, shown at checkout. Orders over 70 lb ship by freight for a flat $99.
- Unused parts can be returned within 30 days. Some items are marked no-refund in their description.
Full details are on our shipping and returns page.
Guides for this part
B58 Downpipe Install Guide: Gen 1 F-Chassis, Gen 2 G-Chassis and the GR Supra
A B58 downpipe swap is a bolt-on job. You undo one V-band clamp at the turbo, the joint at the mid pipe and a support bracket, move the two oxygen sensors over, and fit the new pipe with a fresh turbo gasket. Plan on 2 t
Best B58 Mods, In the Order to Do Them
Start with a tune. It is the biggest gain per dollar on any B58. Then add a downpipe and a Stage 2 map, then an upgraded high-pressure fuel pump (HPFP) and an ethanol blend. Only after that should you think about a bigge
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