Active Autowerke BMW G2X B58 M340i M440i Active Aflow Catted Downpipe (2024 and older)

BMW introduced a new valvet ronic, single turbo version of its direct-injection engine for the later F-Chassis models beginning in 2016 and carried over to the G-chassis models. The Active Autowerke B58 downpipe for the M340i and M440i helps unleash some of the potential that is restricted by the OEM downpipe.

Turbochargers are powered by spent exhaust gases created during the combustion process. The quicker these gases are evacuated, the better. Unfortunately, the factory down pipe in the B58 is quite restrictive, which results in slower exhaust gases and slower turbo spool.

The Active Autowerke B58 Signature down pipe utilizes 4.5 diameter stainless steel piping in order to provide more power, quicker spool, and extreme durability. It then tapers down to 3.5" where we've incorporated a stainless flex joint and then down to 80mm to meet the OEM exhaust system. We never drop the diameter less than the stock diameter of 80mm. 

This variant includes a 4.5" Active Aflow catalytic converter that will NOT produce a CEL for cat efficiency guaranteed by Active Autowerke (full replacement within first two years of ownership).

The Active Aflow super high output catalytic converter features full 304 stainless steel construction, including the substrate. Active Aflow Catalytic Converters are EPA registered and compliant in 49 states and fully OBD2 compliant, perfect for use on 1996 and newer vehicles. Active's proprietary precious metal loading technology ensures greatly reduced emissions, eliminating most "Check Engine Lights" due to cat efficiency errors. These high flow catalytic converters outperform stock converters and provide a reliable solution to the most common catalytic converter problems.

The Active Aflow Catalytic Converters are rated for engines putting out up to 800 horsepower while maintaining a high flow capacity. The reduced back-pressure from this high flow catalytic converter will allow you to maximize your engines horsepower without the harmful emissions. Say goodbye to Check Engine Lights for cat efficiency and failed emissions tests!

Please Note: These catalytic converters are not legal for use on vehicles registered in the state of California as a result of California Vehicle Code Section 27156 and 38391.