The Active Autowerke B58 downpipe for the 340i 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 G20 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 to smaller than the stock diameter of 80mm.
This variant includes a 4.5" high flow GESI catalytic converter that will NOT produce a CEL! GESI has stamped N/GBL/4389/1119 on these cats as required by the EPA. The number represents the following: N (New) GBL: GESI’s Manufacturer Code / 4389 is the part number registered with the EPA / 1119: Manufacturing Month and Year. GESI can correctly claim that this specific technology has met test protocol 40CFR86, and has been verified by a third party laboratory, and most importantly has been registered with the EPA.
NOTE: Federal law prohibits the tampering of an emissions control device. Mobile Source Enforcement Memorandum 1A, allows for aftermarket parts to be used in the repair or replacement of emissions control systems, provided the emissions aren’t adversely affected. There is no mention or reference to cell density or converter volume dimension. The GESI catalytic converter will produce emissions that will meet the standards set by the EPA, not CARB.
The speed of a turbo’s impeller wheel is limited by exhaust back pressure. A larger down pipe relieves some of this pressure, resulting in quicker and more efficient spool. With Active Autowerke’s Signature downpipe, your B58 can rev quicker, and deliver more horsepower and torque.
Minimizing back pressure while retaining daily drive-ability was the goal of our B58 downpipe. Owners can now upgrade to a product that is affordable, reliable, and easy to install.
After months of research and development, our engineers settled on a 4.5” diameter pipe which utilizes the least number of bends possible. The large volume helps the turbo spool as quickly as possible by eliminating back pressure during spool up. We are ushering in a new era in performance where we maintain air control standards without significant losses in power by using the GESI super high output catalytic converter in our signature downpipe.
Constructed entirely from 304 stainless steel with 1.5MM wall thickness, we are confident that you’ll be pleased with how robust and durable this down pipe is. Trouble-free installation and a long lifespan ensure that you’ll enjoy many miles of performance with your B58!