Description
Maximize the performance of your BMW’s latest-generation turbocharged engine with the Active Autowerke B58N Gen-3 GESI Catted Downpipe, engineered specifically for 2025+ M340i and M440i models equipped with the B58N Gen-3 engine. Designed to reduce exhaust restriction while maintaining emissions efficiency, this downpipe delivers faster turbo spool, increased horsepower, and improved throttle response.
The factory B58N Gen-3 downpipe integrates a restrictive Gasoline Particulate Filter (GPF), limiting exhaust flow and overall performance. Active Autowerke addresses this with a 5-inch diameter 304 stainless steel downpipe, optimized for maximum flow and durability, while tapering to 80mm to seamlessly connect with the OEM exhaust system.
This version features a GESI G-Sport Ultra High Output catalytic converter, providing industry-leading emissions control without sacrificing performance. Fully EPA-registered and OBD2 compliant, the GESI catalyst is designed to eliminate check engine lights (CEL) while supporting builds up to 1,000 horsepower.
Key Features & Benefits
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GESI G-Sport UHO High-Flow Catalytic Converter – EPA registered & OBD2 compliant
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No CEL Guarantee – optimized catalytic efficiency
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5” Mandrel-Bent 304 Stainless Steel Piping – maximizes exhaust flow
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Quicker Turbo Spool – reduced backpressure improves boost response
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Rated Up to 1,000 HP – ideal for high-performance builds
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TIG-Welded Construction – superior strength and durability
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Casted Stainless Steel V-Band Flange – precise OEM-style fitment
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400 CPSI High-Flow Catalyst – balances emissions and performance
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Withstands Up to 1500°F – engineered for extreme conditions
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Fast Light-Off Time – reaches operating efficiency in ~9 seconds
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Bolt-On Installation – no cutting or welding required
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Made in USA (Miami, Florida)
Performance Benefits
By significantly reducing exhaust backpressure, this downpipe allows the turbocharger to operate more efficiently. The result is quicker spool, increased horsepower and torque, and smoother power delivery, all while maintaining daily drivability and emissions-conscious performance.
Active Autowerke’s engineering focuses on maximizing airflow with minimal bends, ensuring optimal exhaust velocity and improved engine efficiency without compromising reliability.
Installation Notes
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Fits US-spec vehicles only (fitment not guaranteed for international models)
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Requires removal of factory GPF downpipe
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Subframe must be dropped – installation time ~9–10 hours
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Professional installation strongly recommended
Important Compliance Note
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EPA compliant for 49 states (NOT legal in California)
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Designed for OBD2 vehicles (1996+)
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Warranty may be void if excessive burble tunes are used (can damage catalytic core)
Warranty
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5 Year / 50,000 Mile Warranty (shell & tubing)
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2 Year / 25,000 Mile Warranty (catalytic core)
Vehicle Fitment
BMW B58N Gen-3 (2025+ US Models Only)
3 Series (G20 LCI)
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2025+ BMW M340i
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2025+ BMW M340i xDrive
4 Series (G22 / G23 / G26)
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2025+ BMW M440i Coupe
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2025+ BMW M440i xDrive Coupe
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2025+ BMW M440i Convertible
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2025+ BMW M440i xDrive Convertible
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2025+ BMW M440i Gran Coupe
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2025+ BMW M440i xDrive Gran Coupe
