BMW B58 4.5" Catless Downpipe for F30/F34 340i, M240i, 440i, 540i & X3 M40i

SKU: XKV21076
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Fitment & Specs
2016-2018 F30 340i; 2017-2019 F34 340i GT; 2017-2021 F22 M240i; 2017-2020 F32/F33/F36 440i; selected early G30 540i, G11/G12 740i, G01 X3 M40i and G02 X4 M40i.
T304 Stainless Steel · Vehicle-Specific Replacement · Professional Installation Recommended
Before You Buy: Off-road/racing use only · Professional install recommended · May Be Required Depending on Setup
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Description

This 4.5-inch catless downpipe is designed for selected BMW B58 3.0L turbocharged inline-six applications. Fitment covers listed BMW 340i, M240i, 440i and selected early B58-powered 540i, 740i, X3 M40i and X4 M40i models.

Built with T304 stainless steel tubing, TIG-welded joints, smooth-radius bends and a CNC-machined flange, this application-specific downpipe is intended for compatible turbo-side and downstream exhaust connections.

Engine BMW B58 3.0L Turbo
Product Type Catless Downpipe
Nominal Diameter 4.5 Inch
Material T304 Stainless Steel

Product Features

  • Vehicle-Specific Design: Intended for the selected BMW B58 applications listed in the fitment tables below.
  • Stainless Steel Construction: T304 stainless steel tubing with TIG-welded joints.
  • Tube and Flange Design: Smooth-radius tubing bends and a CNC-machined flange.
  • Catless Configuration: One replacement downpipe assembly without an integrated catalytic converter.

Vehicle Fitment

This downpipe is listed for selected BMW B58 3.0L turbo applications. Match your exact model year, chassis, engine version and exhaust connections before ordering.

BMW F-Series Applications

Vehicle Model Years Chassis Engine / Notes
BMW 340i / 340i xDrive 2016–2018 F30 B58 3.0L Turbo
BMW 340i xDrive Gran Turismo 2017–2019 F34 B58 3.0L Turbo
BMW M240i / M240i xDrive 2017–2021 F22 Selected B58 Coupe applications
BMW 440i / 440i xDrive 2017–2020 F32 / F33 / F36 Selected B58 Coupe, Convertible and Gran Coupe

Selected Early BMW G-Series Applications

Vehicle Model Years Chassis Engine / Notes
BMW 540i / 540i xDrive Selected 2017–2019 G30 Early B58 applications
BMW 740i / 740i xDrive Selected 2017–2019 G11 / G12 Early B58 applications
BMW X3 M40i 2018–2019 G01 Selected early B58 applications
BMW X4 M40i 2019 G02 Selected early B58 application
Fitment Notice

The model years and chassis listed above refer to selected BMW B58 applications. Engine family alone does not guarantee downpipe compatibility. Turbocharger connection design, exhaust outlet, sensor arrangement and mounting geometry can vary by vehicle and engine revision.

For early G-Series vehicles, confirm the exact B58 engine version and physical connections before purchasing.

Product Specifications

Product Catless Exhaust Downpipe
Engine Family BMW B58 3.0L Turbo
Nominal Diameter 4.5 Inch
Material T304 Stainless Steel
Construction TIG-Welded Tubing
Tube Design Smooth-Radius Bends
Flange CNC-Machined
Configuration Catless

The 4.5-inch dimension is the listed nominal product specification. Exact turbo-side and outlet connection dimensions should be verified for the intended application.

Before You Buy

To help confirm that you are selecting the correct downpipe, please review the following:

  1. Vehicle and engine: Check the exact model year, chassis, drivetrain and B58 engine version.
  2. Turbo-side connection: Compare the turbocharger flange or clamp arrangement with the original part.
  3. Exhaust outlet: Verify downstream pipe connection dimensions, alignment and mounting locations.
  4. O2 sensors: Check the number, position and orientation of the required sensor connections.
  5. Installation clearance: Confirm bracket alignment and available space, including any drivetrain-specific differences.

Important: This is not a universal downpipe for every BMW B58-powered vehicle. Later-generation applications such as G20 M340i, G22 M440i, G42 M240i and Toyota Supra are not confirmed by the fitment tables above. Do not assume compatibility based on the B58 engine name alone.

Package Includes

  • 1 × 4.5" Catless Downpipe Assembly

Additional hardware, clamps or sensor components are not specified in this listing. Confirm package contents if your installation requires specific hardware.

Installation Notes

  • Professional installation is recommended.
  • Confirm the turbo-side connection, downstream exhaust connection and O2 sensor layout before installation.
  • Check mounting points, brackets and surrounding clearance before final assembly.
  • Supporting ECU calibration or tuning may be required depending on the vehicle setup; no tuning device is listed as included.

Emissions & Legal Notice

This product has a catless configuration and is not represented as street-legal or emissions-compliant for vehicles subject to applicable emissions controls. Removing, disabling or bypassing required emissions equipment may violate U.S. federal, state or local law. Do not purchase or install this product for a prohibited application. A racing or off-road designation does not itself provide a legal exemption.

Shipping & Return

SHIPPING & DELIVERY
Fast Processing & Reliable Transit

  • Processing: Orders are processed and shipped from the nearest available warehouse within 1 business day after payment.
  • Delivery: Estimated delivery time is approximately 3–4 business days after shipment.
  • Shipping - Free shipping on all orders within the contiguous 48 U.S. states.

RETURNS & EXCHANGES
30-Day Hassle-Free Policy

  • Return Window: We offer a 30-day return policy from the date of delivery.
  • Item Condition: Returned items should be unused, uninstalled, and in their original packaging when possible.
  • Return Process: To initiate a return or exchange, please contact our customer service team first to receive authorization and instructions.

WARRANTY
2-Year Limited Replacement Warranty

  • Duration: All products are backed by a 2-year limited warranty.
  • Coverage: This warranty covers manufacturing defects and product failures under normal use, and provides a replacement for qualified cases (repairs are not performed).

CUSTOMER SUPPORT
We’re Here to Help – Contact Us First

  • Priority Contact: For any order-related issues—including returns, warranty claims, or general inquiries—please contact us first before taking further action. We are committed to resolving your concern promptly.
  • Feedback Notice: If you are unsatisfied, we kindly ask that you allow us an opportunity to address the issue before leaving neutral or negative feedback.
  • Email Support: You can reach us at support@XKVracing.com.

Downpipe Buying Guide

A Key Section in a Turbocharged Exhaust System

The downpipe connects directly to the turbocharger and routes exhaust gases into the rest of the exhaust system. It is one of the first exhaust components downstream of the turbo.

Because of its position, the design of the downpipe influences how exhaust gases move away from the turbo and into the remaining exhaust path.

What Drivers May Observe

More consistent exhaust flow downstream of the turbocharger

Reduced restriction compared to some factory exhaust layouts

Smoother boost delivery under certain operating conditions

Changes in exhaust tone, depending on system setup

Catted vs Catless

Catted Downpipe

Includes a catalytic converter designed for specific applications
Used where emissions considerations or regulations apply
Often selected for vehicles intended for street use, where permitted

Catless Downpipe

Does not include a catalytic converter
Typically intended for off-road, competition, or export use
Used in applications where different regulatory standards apply

Is a Downpipe Right for Your Build?

Own a turbocharged vehicle

Are upgrading intake, intercooler, or exhaust components

Want improved exhaust efficiency and response

Are building a balanced street or track setup

FAST SHIPPING

Ships within 1 business day after payment
3–4 business day delivery

Secure and Reliable Checkout

Secure checkout with major payment options

LOCAL WAREHOUSE

Orders ship from U.S. warehouses when available

Easy Returns and Exchanges

30-day returns for eligible unused items

Parts Warranty

Warranty support for qualified manufacturing defects

Important Notice

Products on this site are intended for off-road, racing, or closed-course use where emissions laws apply. They are not represented as street legal, emissions-compliant, or legal for use on public roads unless explicitly stated.

Some products may remove, replace, relocate, disable, or alter emissions-related components, including but not limited to catalytic converters, EGR, DPF, SCR, DOC, O2 sensors, or related factory systems. Compatible tuning, calibration, or supporting modifications may be required to avoid engine codes or drivability issues.

Professional installation is recommended. Buyers are responsible for verifying product compatibility, local regulations, emissions requirements, and any required tuning or supporting modifications before purchase and installation.

Performance gains, sound changes, airflow improvements, temperature changes, fuel economy changes, fitment, and drivability results may vary. No specific performance gains are guaranteed.

Downpipe FAQs

What is a downpipe? +

A downpipe is the exhaust section that connects to the turbocharger and routes exhaust gases toward the rest of the exhaust system. Depending on the vehicle and product design, an upgraded downpipe may help reduce exhaust restriction and support improved turbo response when paired with the right setup.

What's the difference between catted and catless downpipes? +

A catted downpipe includes a catalytic converter, while a catless or racing downpipe does not include one and may alter or remove emissions-related equipment. Catless or racing downpipes are generally intended for off-road, racing, or closed-course use where emissions laws apply. Always check the product details and local regulations before purchase.

Will a downpipe increase horsepower? +

A downpipe may support improved exhaust flow and power potential when combined with proper tuning and supporting modifications. Horsepower and torque gains are not guaranteed and will vary depending on the vehicle, engine condition, tune, fuel, turbo setup, and overall exhaust system.

Do downpipes make the vehicle louder? +

A downpipe can change exhaust tone and may increase turbo or exhaust sound depending on the vehicle, whether the downpipe is catted or catless, and the rest of the exhaust system. Final sound level varies by setup.

Do I need tuning after installing a downpipe? +

Tuning requirements depend on the vehicle, downpipe design, emissions equipment, O2 sensor setup, and supporting modifications. Some applications may require compatible tuning or calibration to support drivability and reduce the chance of warning lights or engine codes.

Will a downpipe trigger a check engine light? +

It may, depending on the vehicle, catalytic converter configuration, O2 sensor location, and ECU calibration. Catless or racing downpipes are more likely to require supporting calibration or sensor-related solutions. Always verify the product notes and tuning requirements before installation.

Are downpipes street legal? +

Street legality depends on the downpipe design, emissions equipment, vehicle application, and local regulations. Catless, racing, or emissions-altering downpipes are generally intended for off-road, racing, or closed-course use where emissions laws apply and are not represented as street legal unless explicitly stated.

Can I use a downpipe with my stock exhaust system? +

Compatibility with a stock exhaust system depends on the vehicle and the specific downpipe design. Some downpipes are designed to connect to factory-style exhaust sections, while others may require compatible aftermarket exhaust parts, adapters, clamps, gaskets, or fabrication. Always check the product fitment and installation notes before ordering.

Are downpipes hard to install? +

Installation difficulty varies by vehicle. Some applications require tight access around the turbocharger, O2 sensors, heat shields, transmission area, or underbody. Rusted factory hardware and limited clearance can also increase installation difficulty. Professional installation is recommended.

Will a downpipe affect reliability? +

Reliability depends on product fitment, installation quality, tuning or calibration, heat management, sensor placement, gasket sealing, fastener condition, and the vehicle’s overall condition. Incorrect installation or mismatched tuning may cause drivability issues.

What should I verify before buying a downpipe? +

Verify your year, make, model, engine, turbo setup, emissions configuration, catalytic converter requirements, O2 sensor layout, flange or clamp connection, exhaust compatibility, and any tuning or calibration needs before purchase.