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Active

B58 Catted Downpipe

$1,199.00

SKU: B58CATDP

In Stock
In Stock
Ships by Sep 12
Free Shipping over $200
$100 Minimum Order
30 Days Return
INSTALL DIFFICULTY
DIY PRO SHOP

Moderate — 2–4 hours

Overview

The Active Autowerke BMW G2X G4X B58 M340i M440i GESI Catted Downpipe is a performance exhaust component designed to improve exhaust gas evacuation. It features a 4.5-inch diameter stainless steel piping that reduces back-pressure, allowing for quicker turbo spool and increased horsepower. This downpipe incorporates a GESI G-Sport Ultra High Output catalytic converter that is EPA registered and OBD2 compliant.
Show original supplier description
The Active Autowerke B58 Signature Catted Downpipe is engineered to unlock the performance potential of the BMW B58 engine by replacing the restrictive OEM downpipe. Constructed from durable TIG-welded 304 stainless steel with a 1.5MM wall thickness, this downpipe utilizes 4.5-inch diameter piping to minimize exhaust back pressure and promote quicker turbo spool. It integrates an Active Aflow catalytic converter, which is EPA registered, OBD2 compliant, and designed to prevent "Check Engine Lights" for cat efficiency, guaranteed by Active Autowerke for the first two years of ownership. This catalytic converter is rated for engines up to 800 horsepower and operates efficiently within 9 seconds of startup, while withstanding temperatures up to 1500°F. The downpipe tapers to 3.5 inches with a stainless flex joint before meeting the OEM exhaust system at 80mm, ensuring it never drops below the stock diameter. The catalytic converter substrate is also 304 stainless steel and furnace brazed for durability. Active Autowerke guarantees no CEL for catalytic efficiency with this downpipe. It is EPA compliant for use on OBD2 vehicles (1996 and newer) except in California. This downpipe is made in Miami, Florida.

Product descriptions are provided by our supplier partners and may not always be perfectly accurate. Not sure this fits? or call (760) 282-4645 and we’ll verify before you order.

Fitment

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Specifications

BrandActive
Part NumberB58CATDP
CategoryExhaust

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Returns & Fitment

Built for enthusiasts. Every order is backed by our 30 day return window on eligible items. Unused and uninstalled products may be returned with approved RMA and no restocking fees when received in new condition. Orders placed through the MOTORMIA app with a complete build qualify for our Fitment Guarantee — free return shipping if the part doesn’t fit your exact setup. The guarantee covers fit only; installation must follow manufacturer instructions, and we recommend a qualified shop for parts marked Difficulty 4–5.

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Shipping

Orders are processed in 1–3 business days. In stock parts ship promptly from our partner network. Special-order items either aren’t currently stocked or are built to your spec — expect 4–6 weeks. If a part goes on backorder while your order is in the queue, we’ll reach out and work through discounted alternatives together.

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