Active Autowerke GESI Catted Downpipe – BMW M240i / 340i / 440i (B58, F3x)

OVERVIEW

BMW introduced a new valvetronic, single-turbo version of its direct-injection engine for the later F-chassis models from 2016, and the restrictive OEM downpipe slows exhaust flow and turbo spool. Active Autowerke's 4.5 inch pipe uses the fewest bends possible, tapering to 3.5 inch at a stainless flex joint and then to 80 mm to meet the OEM exhaust — never dropping below the stock 80 mm — so back pressure is kept to a minimum while daily drivability is retained. This variant carries a 4.5 inch GESi G-Sport Ultra High Output catalytic converter, built in full 304 stainless including the substrate, that keeps emissions low at high flow and will not trigger a check engine light.

SPECS

• 4.50 inch diameter piping, tapering to 3.5 inch and then to 80 mm at the OEM exhaust connection
• Diameter is never reduced below the stock 80 mm
• 1.5 mm wall thickness
• 4.5 inch ultra high flow GESi G-Sport catalytic converter, 400 cells per square inch
• Rated for 500 to 850 hp applications
• TIG welded 304 stainless steel construction throughout
• 304 stainless steel catalyst substrate, furnace brazed to the mantle for durability
• Cast upper stainless steel V-band for precise fitment
• Stainless flex joint
• Withstands temperatures up to 1500 F
• Reaches operational efficiency within 9 seconds of startup
• EPA registered, fully OBD2 compliant for 1996 and newer vehicles, except in California
• Suited to forced induction applications with no loss of horsepower
• Bolts on with no cutting or welding required
• Made in Miami, Florida
• Covered by a 5 year / 50,000 mile warranty on the catalytic converter

PARTS INCLUDED

• Complete downpipe assembly as supplied by Active Autowerke; see the installation instructions for the full bill of materials.

TECH RESOURCES

Additional Parts Required

• None. Active Autowerke specifies no additional hardware for this downpipe; it bolts on with no cutting or welding required.
• Optional: Active Autowerke offers this downpipe in a version supplied with a turbo flange gasket. A fresh turbo-to-downpipe gasket is worth having on hand if the factory gasket is not reusable.

Installation

• Active Autowerke catalytic converter break-in instructions (PDF) — follow this procedure on first start-up to avoid a check engine light being set in error
• Active Autowerke installation instruction library

Notes

• 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 Sections 27156 and 38391.
• 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 meet the standards set by the EPA, not CARB.
• Active Autowerke lists further B58 applications for this downpipe beyond the F-chassis models above, including the 540i, 640i, 740i, 840i, M340i, M440i, X3 M40i, X4 M40i, X5 40i, X6 40i, X7 40i and Z4 M40i. This part covers 2024 and older B58 cars. Fitment applies to US-model cars only. Confirm fitment with Speed Logic before ordering.

PART NUMBER

• 11-062

VEHICLE APPLICATIONS