If you are shopping for a B58 Gen 3 downpipe, the first thing to confirm is fitment: Gen 1, Gen 2 and Gen 3 B58 downpipes are not interchangeable just because the engine family name is similar. For AZ Motorsport shoppers, the Gen 3 LCI listing is the B58 BMW M340i/M440i (G20/G22) Downpipe GEN3 LCI, while separate AZM listings exist for Gen 2 G20/G22/G42 cars and Gen 1 F-chassis cars.
The second thing to confirm is your tune and CEL plan. A downpipe can change sound, flow and turbo response, but it can also affect oxygen-sensor behaviour, catalyst-efficiency monitoring, smell, readiness expectations and local road-use questions. Do not order from a horsepower number alone; match the car first, then plan the software and installation details.
For Quebec, Montreal and Brossard buyers, the practical answer is simple: send AZ Motorsport the exact year, chassis, VIN if uncertain, pre-LCI/LCI status, current tune, fuel plan and whether you want a catted or catless setup before booking the install.
Quick answer: B58 Gen 3 downpipe checklist
| Question | Short answer | What to verify |
|---|---|---|
| What is a B58 Gen 3 downpipe? | It is the downpipe direction for newer B58 Gen 3 / LCI-style applications, including AZM’s M340i/M440i G20/G22 GEN3 LCI listing. | Confirm the exact AZM product page, year, chassis, LCI status and VIN if uncertain. |
| Is Gen 3 the same as Gen 1 or Gen 2? | No. AZM lists separate B58 GEN1, GEN2 and GEN3 downpipe products. | Do not buy from engine name alone; match generation and chassis. |
| Does an M340i downpipe need a tune? | A tune is commonly part of a performance downpipe plan, but the right answer depends on the car, ECU, fuel, catalyst style and goals. | Confirm tuner support before the install, especially if you expect Stage 2-style performance or CEL management. |
| Will a catless B58 Gen 3 downpipe cause a CEL? | It can. Catless setups generally carry the highest CEL/readiness risk. | Ask your tuner/installer about O2 sensor behaviour, software strategy and local requirements. |
| Catted or catless? | Catted is usually the more street-friendly compromise; catless is the more aggressive sound/flow direction. | Verify smell tolerance, sound goals, road-use expectations, tune plan and product variant. |
| Can it add horsepower? | It can support more performance as part of the right hardware/tune/fuel package, but an exact HP number is not universal. | Ask for dyno context: car, tune, fuel, turbo, dyno type and all supporting hardware. |
| Best next step | Match the car to the correct AZM B58 downpipe product, then contact AZ Motorsport if anything is unclear. | Use the BMW downpipes collection and send vehicle details before ordering. |
Useful AZ Motorsport links:
- B58 BMW M340i/M440i (G20/G22) Downpipe GEN3 LCI: /products/bmw-b58-gen-3-downpipe
- B58 BMW M340i/M440i/M240i (G20/G22/G42) Downpipe GEN2: /products/b58-downpipe-catless-for-2019-bmw-m340i-m440i-m240i-x5-40i-xdrive-g20-g22-g26-g05
- B58 BMW M240i/340i/440i/540i (F22/F30/F32) Downpipe GEN1: /products/b58-bmw-m240i-340i-440i-540i-f22-f30-f32-downpipe-gen1
- BMW downpipes collection: /collections/bmw-downpipes
- B58 downpipe fitment guide: /blogs/guides/b58-downpipe-fitment-gen1-gen2-gen3-lci
- BMW downpipe tune and CEL checklist: /blogs/guides/bmw-downpipe-tune-check-engine-light-fitment-checklist
- Catted vs catless downpipe guide: /blogs/guides/catted-vs-catless-downpipe-sound-smell-cel-tune-quebec
- Contact AZ Motorsport: /pages/contact
B58 Gen 1 vs Gen 2 vs Gen 3 downpipe fitment signals
A B58 downpipe search can mean several different cars. Someone searching “m340i downpipe” may own a G20 M340i, while someone searching “340i downpipe” may own an F30 340i. Someone searching “gen 3 b58 downpipe” may be trying to separate a newer LCI-style application from earlier G20/G22/G42 fitment.
Use the table below as a buyer checklist, not a guarantee. The product page, VIN, chassis and current vehicle details should always win over a generic year/model assumption.
| B58 buyer signal | AZM product direction | Fitment caution |
|---|---|---|
| F22/F30/F32, M240i/340i/440i/540i, older B58 searches | B58 BMW M240i/340i/440i/540i (F22/F30/F32) Downpipe GEN1: /products/b58-bmw-m240i-340i-440i-540i-f22-f30-f32-downpipe-gen1 | This is the F-chassis direction. Do not assume it fits a G20 M340i or G22 M440i. |
| G20/G22/G42, M340i/M440i/M240i Gen 2 searches | B58 BMW M340i/M440i/M240i (G20/G22/G42) Downpipe GEN2: /products/b58-downpipe-catless-for-2019-bmw-m340i-m440i-m240i-x5-40i-xdrive-g20-g22-g26-g05 | This is the Gen 2 product direction. If the car is newer/LCI or the buyer is searching “Gen 3,” confirm before ordering. |
| G20/G22 M340i/M440i, LCI, Gen 3 B58 searches | B58 BMW M340i/M440i (G20/G22) Downpipe GEN3 LCI: /products/bmw-b58-gen-3-downpipe | This is the Gen 3 LCI product direction. Still confirm VIN/year/chassis and product-page fitment before purchase. |
| Buyer only knows “B58” | Start at the BMW downpipes collection: /collections/bmw-downpipes | “B58” by itself is not enough to choose a downpipe. Get year, model, chassis, drivetrain and VIN if needed. |
The safest ordering rule is: never use badge name alone. “M340i,” “M440i,” “G20,” “G22,” “LCI,” “Gen 2” and “Gen 3” all matter because downpipe geometry, sensor placement and fitment can change between applications.
What is a B58 Gen 3 downpipe?
A B58 Gen 3 downpipe is the front exhaust/downpipe upgrade direction for the newer Gen 3 / LCI B58 application rather than the earlier Gen 1 or Gen 2 B58 fitment paths. On AZ Motorsport, the relevant Gen 3 product is listed as B58 BMW M340i/M440i (G20/G22) Downpipe GEN3 LCI.
That does not mean every BMW with a B58 badge should use the Gen 3 part. AZM also has separate B58 GEN2 and GEN1 products. If your search starts with “gen 3 b58 downpipe stock,” “gen 3 b58 downpipe catted,” “gen 3 b58 catless downpipe” or “bmw gen 3 b58 downpipe,” the next step is to confirm the exact vehicle before choosing a variant.
Catted vs catless B58 Gen 3 downpipe checklist
AZM’s verified Gen 3 listing includes Race (Catless) and High Flow (Catted) variant directions. The right choice depends on how the car is used, not just what sounds most aggressive in a video.
| Choice | Why buyers consider it | Trade-offs to understand | Buyer checklist |
|---|---|---|---|
| High Flow (Catted) | Usually chosen by owners who want a more balanced street/daily-driver direction while changing sound and flow. | A catted downpipe is not a universal no-CEL, no-smell or road-compliance guarantee. | Ask about tune support, catalyst monitoring, smell tolerance, local requirements and daily winter use. |
| Race (Catless) | Usually chosen for the most aggressive sound/flow direction and for more performance-focused setups. | Highest smell, CEL/readiness and road-use concern. Cold starts and odour may be more noticeable. | Confirm the car’s purpose, tune plan, inspection expectations, O2 sensor strategy and whether the owner accepts the trade-offs. |
| Stay stock downpipe for now | Sensible if the buyer mainly wants controlled sound and is not ready for tune/CEL questions. | Less downpipe/turbo character than a downpipe upgrade. | Consider whether an exhaust-system change better matches the goal before modifying the downpipe. |
If the car is a Quebec daily driver, this choice deserves extra attention. Cold starts, condo garages, neighbourhood sound tolerance, winter use and road-salt exposure can all change what feels acceptable after the install.
Tune and CEL planning before installation
A B58 Gen 3 downpipe should not be treated as a part-only decision. It should be planned with the tuner and installer because the downpipe can affect exhaust flow and how the ECU sees catalyst and oxygen-sensor behaviour.
Before ordering, ask:
- Is the car stock tune, Stage 1, Stage 2 or custom tuned?
- Does the tuner support this exact year, ECU and B58 generation?
- Is the car running pump gas, ethanol blend or another fuel plan?
- Is the goal sound, turbo response, peak power, drivability or a specific dyno result?
- Is the buyer expecting no check engine light or emissions-readiness behaviour?
- Will tuning, logging or post-install checks happen the same day as installation?
- Is the vehicle used on public roads, track days, off-road/race events or a mix?
The honest answer to “will it throw a CEL?” is not a guarantee. A CEL can happen when the ECU detects catalyst-efficiency or O2-sensor behaviour outside the expected range. Catless setups generally carry the highest risk; catted setups may reduce risk, but they are not a universal fix. Confirm your hardware, software and road-use expectations before the car is on the lift.
For broader reading, see AZM’s BMW downpipe tune/CEL checklist: /blogs/guides/bmw-downpipe-tune-check-engine-light-fitment-checklist and the guide on whether a downpipe needs a tune: /blogs/guides/downpipe-guide-tune-needed.
M340i downpipe and tune HP: why exact horsepower claims need context
Many shoppers search “m340i downpipe and tune hp” or “m340i hp after downpipe and tune” because they want a simple number. The safer answer is that a downpipe can support more power as part of the right tune and hardware package, but a universal horsepower claim is not a reliable buying guide.
Before trusting any HP number, ask what it was measured on:
| Variable | Why it matters |
|---|---|
| Exact car and B58 generation | Gen 1, Gen 2 and Gen 3 cars are not the same fitment or calibration question. |
| Tune | Stock tune, off-the-shelf tune, Stage 2-style calibration and custom dyno tuning can produce different results. |
| Fuel | Pump gas, ethanol blends and fuel quality can change output and safety margins. |
| Hardware | Intake, exhaust, turbo, intercooling and downpipe style all affect the total setup. |
| Dyno and conditions | Dyno type, correction factor, temperature and baseline method can change the number shown. |
| CEL/readiness strategy | A car tuned for a dyno graph may not match a buyer’s daily-driver or inspection expectations. |
For AZM buyers, the right question is not “what number will this downpipe make on every M340i?” The right question is “does this exact downpipe match my car, tune, fuel and usage plan?” If a seller cannot explain the context behind a horsepower claim, treat the number as incomplete.
Quebec, Montreal and Brossard buyer checklist
A B58 Gen 3 downpipe on a Quebec daily driver is not the same decision as a weekend-only car in a warm climate. Local buyers should think about the full ownership experience before choosing catted or catless.
Ask AZ Motorsport or your installer:
- Which B58 generation does my car use: Gen 1, Gen 2 or Gen 3?
- Does my VIN/year/chassis match the Gen 3 LCI product page?
- Is my car pre-LCI or LCI?
- Which variant makes sense for my use: Race (Catless) or High Flow (Catted)?
- What should I expect for cold-start sound, cabin character and smell?
- What does winter use and road salt mean for installation hardware and future service?
- Should gaskets, clamps or related hardware be inspected or replaced during installation?
- Should tuning be completed before, during or after the install appointment?
- What should I understand about CEL/readiness behaviour before driving home?
- If road compliance matters, what local rules or inspection expectations should I confirm before modifying the car?
This article is not legal advice and does not guarantee emissions compliance, inspection results or road legality in Quebec or anywhere else in Canada. If compliance matters for your car, check current local rules and speak with your installer/tuner before buying.
What details should you send AZ Motorsport before ordering?
Send enough information for the team to help you avoid the wrong product path:
- Year, make and model.
- Chassis code if you know it: G20, G22, G42, F30, F32, etc.
- VIN if there is any uncertainty.
- Pre-LCI or LCI status if known.
- Current tune status: stock, Stage 1, Stage 2, custom or unknown.
- Fuel plan: pump gas, ethanol blend or other.
- Current exhaust/downpipe hardware.
- Desired variant: catted/high-flow catted or catless/race.
- Main goal: sound, response, horsepower, track use, daily drivability or a balanced setup.
- Concerns: CEL, smell, cold start, inspection/readiness, winter driving or installation timing.
If you are unsure, start with the BMW downpipes collection at /collections/bmw-downpipes and contact AZ Motorsport through /pages/contact with your vehicle details.
FAQ: B58 Gen 3 downpipe fitment, tune and buyer questions
What is a B58 Gen 3 downpipe?
A B58 Gen 3 downpipe is the downpipe direction for newer Gen 3 / LCI B58 applications. On AZ Motorsport, the Gen 3 listing is the B58 BMW M340i/M440i (G20/G22) Downpipe GEN3 LCI. Confirm your exact year, chassis, VIN and product-page fitment before ordering.
How do I know if my BMW needs a Gen 1, Gen 2 or Gen 3 B58 downpipe?
Start with chassis and generation, not the B58 name alone. AZM lists GEN1 for F22/F30/F32 M240i/340i/440i/540i applications, GEN2 for G20/G22/G42 M340i/M440i/M240i applications and GEN3 LCI for G20/G22 M340i/M440i applications. If you are unsure, send AZ Motorsport your year, chassis and VIN before buying.
Does an M340i downpipe need a tune?
A tune is commonly part of a performance downpipe plan, especially when the goal is a Stage 2-style setup, stronger response or CEL management. The right answer depends on the exact car, ECU, catalyst style, fuel, tuner support and road-use expectations. Confirm the tune plan before installation.
Will a catless B58 Gen 3 downpipe cause a check engine light?
It can. A catless downpipe usually carries the highest CEL/readiness risk because catalyst and oxygen-sensor behaviour can change significantly from stock. A tune or hardware strategy may be part of the plan, but there is no universal no-CEL guarantee.
What is the difference between catted and catless B58 downpipes?
A catted or high-flow catted downpipe keeps a catalyst in the downpipe path and is usually the more street-friendly compromise. A catless/race downpipe removes that catalyst path for a more aggressive sound/flow direction, but it usually brings more smell, CEL/readiness and road-use concerns. Confirm local rules and tuning expectations before choosing.
Can an M340i downpipe add horsepower, and what should buyers confirm before trusting HP claims?
A downpipe can support more power as part of the right tune, fuel and hardware package, but an exact horsepower number is not universal. Before trusting a claim, confirm the exact car, B58 generation, tune, fuel, supporting hardware, dyno type, baseline and test conditions.
Does a downpipe change sound or smell on an M340i/M440i?
Yes, a downpipe can make the exhaust character more aggressive and can increase turbo/downpipe sound. Smell depends heavily on catalyst style and setup; catless downpipes usually carry the highest odour risk, while catted setups are usually milder but not smell-free in every case.
What should Quebec/Montreal/Brossard buyers ask before installation?
Ask which B58 generation the car uses, whether the VIN/chassis matches the product page, whether catted or catless makes sense for Quebec daily use, what to expect for cold-start sound and smell, whether tuning is required, and what local road-use or inspection expectations should be checked before modifying the car.
What details should I send AZ Motorsport before ordering?
Send the year, model, chassis code, VIN if uncertain, LCI/pre-LCI status, current tune, fuel plan, current hardware, desired catted/catless direction, main goals and concerns about CEL, smell, sound, winter use or inspection/readiness. That gives AZ Motorsport the context needed to help point you toward the correct B58 downpipe path.
Bottom line
A B58 Gen 3 downpipe is a fitment-specific purchase, not a one-size-fits-all B58 part. Confirm whether your BMW needs GEN1, GEN2 or GEN3 LCI, choose catted or catless based on real usage, and plan tuning/CEL expectations before installation. If any detail is unclear, contact AZ Motorsport with the car’s year, chassis and VIN before ordering.
