Description
Unlock the performance potential of your BMW's latest B58N Gen 3 engine with the Active Autowerke Catted Downpipe. Designed specifically for 2025 and newer BMW M340i and M440i models equipped with the updated B58N engine and integrated Gasoline Particulate Filter (GPF), this premium exhaust upgrade delivers improved turbocharger response, increased exhaust flow, and enhanced driving performance—all without requiring a performance tune.
Available with either the industry-leading GESI Ultra High Output catalytic converter or Active Autowerke's AFlow high-flow catalytic converter, this downpipe is engineered to provide maximum airflow while maintaining excellent emissions performance and eliminating common catalytic efficiency check engine lights.
Constructed entirely from TIG-welded 304 stainless steel, the Active Autowerke Signature Downpipe features a massive 5-inch primary section that tapers smoothly into the factory 80mm exhaust connection, reducing backpressure and allowing the turbocharger to spool faster and operate more efficiently.
No Performance Tune Required
Vehicle Fitment
Fits US-Spec Vehicles Only
- 2025+ BMW M340i (B58N Gen 3)
- 2025+ BMW M340i xDrive (B58N Gen 3)
- 2025+ BMW M440i Coupe (B58N Gen 3)
- 2025+ BMW M440i xDrive Coupe (B58N Gen 3)
- 2025+ BMW M440i Gran Coupe (B58N Gen 3)
- 2025+ BMW M440i xDrive Gran Coupe (B58N Gen 3)
- 2025+ BMW M440i Convertible (B58N Gen 3)
Engine Compatibility
- BMW B58N Gen 3 Turbocharged Inline-6 Engine
Important Note: Fitment applies to US-market vehicles only. Compatibility with non-US models cannot be guaranteed.
Performance Benefits
The factory B58N Gen 3 downpipe incorporates a restrictive catalytic converter and GPF assembly that limits exhaust flow and turbocharger efficiency. The Active Autowerke Signature Downpipe dramatically reduces these restrictions, allowing exhaust gases to exit more efficiently.
Benefits include:
- Faster turbo spool and improved boost response
- Increased horsepower and torque potential
- Improved throttle response
- Reduced exhaust backpressure
- Enhanced engine efficiency
- More aggressive exhaust note
- Retains daily driving comfort
- No performance tune required
Premium Construction
Built for long-term reliability and extreme performance applications, every Active Autowerke B58N Gen 3 Downpipe is manufactured from premium-grade materials.
Construction Features
- Full 304 stainless steel construction
- Precision TIG-welded assembly
- Cast stainless steel upper V-band connection
- 5-inch primary tubing design
- Smooth transition to factory 80mm exhaust
- 1.5mm wall thickness for durability
- Direct bolt-on installation
- No cutting or welding required
Catalytic Converter Options
GESI Ultra High Output Catalytic Converter
The GESI-equipped version utilizes one of the most respected high-performance catalytic converters in the industry.
Features include:
- EPA registered design
- Fully OBD2 compliant
- Ultra-high-flow 400 CPSI catalyst
- Rated for applications up to 1,000 horsepower
- Stainless steel substrate construction
- Proprietary precious metal loading technology
- Significantly reduces check engine light occurrences
- Rapid light-off capability for improved emissions performance
Active AFlow High Output Catalytic Converter
The AFlow version provides exceptional flow characteristics while maintaining emissions efficiency.
Features include:
- EPA registered design
- Fully OBD2 compliant
- Ultra-high-flow 400 CPSI catalyst
- Rated for applications up to 950 horsepower
- Stainless steel substrate construction
- Proprietary catalyst technology
- Excellent emissions control
- Reduced risk of catalytic efficiency faults
Key Features
- Designed for 2025+ BMW M340i and M440i models
- Compatible with B58N Gen 3 engines
- Available with GESI or AFlow high-flow catalytic converters
- No check engine light for catalytic efficiency
- No performance tune required
- Large 5-inch primary tubing
- Faster turbocharger spool
- Increased exhaust flow
- Reduced backpressure
- Enhanced throttle response
- Precision TIG-welded 304 stainless steel construction
- Direct bolt-on installation
- No cutting or welding necessary
- Supports high-horsepower applications
- Made in the USA
Installation Notes
The factory B58N Gen 3 downpipe includes an integrated Gasoline Particulate Filter (GPF), making installation significantly more involved than previous B58 applications.
Important Installation Note: Removal of the factory GPF-equipped downpipe typically requires lowering the subframe and may require approximately 9-10 hours of labor.
Professional installation is strongly recommended.
Emissions Information
- EPA compliant for use on OBD2-equipped vehicles (1996 and newer)
- Not legal for use on vehicles registered in California
- Not CARB approved
- Compliance regulations may vary by state and locality
Warranty
GESI and AFlow Catalytic Converter Warranty
- 5-Year / 50,000-Mile Warranty on shell and tube ends
- 2-Year / 25,000-Mile Warranty on catalytic core
- Warranty applies to original purchaser only
Note: Excessive aftermarket burble or crackle tuning beyond factory levels may damage the catalytic core and void warranty coverage.
Why Choose Active Autowerke?
Manufactured in Miami, Florida, Active Autowerke has earned a reputation for developing premium BMW performance products that combine power, reliability, and precise fitment. The B58N Gen 3 Signature Catted Downpipe continues that tradition by offering enthusiasts a high-quality solution that improves performance while maintaining drivability and emissions efficiency.
Brand: Active Autowerke
Manufacturer Location: Miami, Florida, USA
Material: TIG-Welded 304 Stainless Steel
Catalytic Options: GESI Ultra High Output or Active AFlow High Output
Installation: Direct Bolt-On
Tuning Required: No
Check Engine Light: No CEL for catalytic efficiency faults under normal operation
