BMW M340i/M440i Straight Downpipe with Heat Shield 2019-2023 | WSTN Performance (B58 G20/G22)

The B58 is built for more. This downpipe lets it deliver. The BMW M340i and M440i sit at the intersection of performance and daily usability smooth power delivery, sharp chassis, and the B58 inline-six producing 382hp from the factory. That number grows considerably with the factory restriction removed. This WSTN Performance Straight Catless Downpipe replaces the OEM unit with a straight-through design, complete with an integrated heat shield to maintain thermal management under sustained performance driving. Designed specifically for M340i and M440i applications, this is the downpipe that forms the foundation of any serious B58 build. Built to order, quality checked in Perth, dispatched worldwide. Why Upgrade? ✅ Heat Shield Integrated: Factory-matched heat shielding protects surrounding components and transmission tunnel critical for sustained high-performance use. ✅ Free-Flow Construction: Straight-through design eliminates catalytic restriction the single most impactful exhaust modification for the turbocharged B58. ✅ Tune-Ready Platform: Forms the foundation for ECU tuning software gains are limited without removing this restriction first. ✅ Stainless Steel: Corrosion-resistant, heat-resistant, precision TIG-welded for durability and a consistent fit. ✅ Direct Bolt-On: Replaces factory downpipe at OEM mounting points no modification required. Key Features & Specs Material: Stainless Steel corrosion resistant, built to last Construction: Precision mandrel-bent, TIG-welded joints Type: Catless straight-through with heat shield Heat Shield: Integrated heat shielding included Fitment: Direct bolt-on OEM mounting points Fitment & Compatibility ✔️ BMW M340i / 330i (G20/G21) 2018–2023 (B58, 3.0T) ✔️ BMW M440i / 430i (G22/G23) 2020–2023 (B58, 3.0T) Designed for M340i and M440i with heat shield integration. Also fits non-M 330i and 430i B58 variants. Confirm your exact model before ordering. Technical Note Emissions: Catless straight-through intended for track and competition use. Buyer is responsible for local emissions compliance. Check applicable regulations before fitting to road-registered vehicles. What's In the Box 1 x WSTN Performance Catless Straight Downpipe with Heat Shield Installation Difficulty: 3/5 Requires workshop lift and exhaust experience Time Estimate: 1.5–2.5 Hours Mounting Type: Direct bolt-on to factory turbo outlet and mid-pipe flanges Warranty / Shipping DISCLAIMER WSTN Performance components are designed for track and competition use. To protect your build and ensure a perfect finish, we recommend professional installation by a certified specialist/workshop. It is the buyer's responsibility to ensure modifications comply with local regulations. WARRANTY We stand behind every product we sell. All WSTN Performance products carry a 1 year WSTN Performance warranty as standard. This covers any manufacturing defects, giving you total peace of mind that your upgrade is built to last. View our full Warranty policy page here. SHIPPING We offer tracked worldwide shipping on our entire catalogue. Products marked as “Built to Order” are handmade in 3–5 weeks (check the product page as lead times may vary), personally dispatched from our Perth WA facility. View our full Shipping policy page here. RETURNS We offer returns on all products if items are damaged or there is something wrong. If we ever make a mistake, we'll cover the return shipping to make it right. View our full Return policy page here. SUPPORT Need a hand with fitment, shipping, or a return? Our Perth-based team is here to help you get your build perfect. Email: contact@wstnperformance.com Sound Clip