Stone Exhaust Eddy Catted Downpipe with GPF/OPF for BMW B58D & Toyota GR Supra A90 – G20 M340i/M340i xDrive, G21 340i xDrive, G29 Z4 M40i – Euro 6 Compliant, No CEL (A223E)

High Flow Sports Catalyst Front Section for B58D and A90 Supra

Unleash faster spool, stronger mid-range and a richer, motorsport tone with Stone Exhaust’s Eddy catalytic front pipe. Built for vehicles with gasoline particulate filters, this GPF and OPF compatible primary cat section offers serious performance without the hassle. It is Euro 6 compliant, MOT friendly and designed to run without engine management lights or fault codes on supported applications.

Part Number: A223E

What makes the Eddy catalyst special

• Patented Eddy flow core spins exhaust gas to enhance conversion efficiency while maintaining ideal turbine back pressure for power.
• Variable behaviour core acts like a low-cell performance cat when you are on throttle, then like a finer-cell catalyst during cruise for clean emissions and smooth drivability.
• No EML and no error messages thanks to optimised lambda sensor positioning that preserves accurate feedback to the ECU.
• Direct-fit to factory turbo outlet and OE brackets. No cutting. No coding. No additional hardware required on listed models.
• Constructed from premium SUS304 stainless steel for long term durability and corrosion resistance.
• Precisely formed with 7-axis CNC mandrel bends for exceptional roundness and uninterrupted gas flow.
• 3D scanned and CAD modelled to follow OEM routing and clearances for a perfect fit on B58D platforms.
• Criss-cross overlap TIG welds at heat-critical joints for strength you can rely on under sustained boost.
• Euro 6 compliant design for road use where applicable.

Real gains you can feel

Expect earlier boost, sharper throttle response and a deeper, more refined soundtrack without intrusive drone. We have installed this unit on our own builds and customer cars at MJ Modifications and feedback has been excellent, with owners praising the improved punch and seamless integration with factory systems.

Vehicle applications

BMW B58D engine

• G20 M340i 2018+
• G20 M340i xDrive 2018+
• G21 340i xDrive 2018+
• G29 Z4 M40i 2019+

Toyota

• GR Supra A90 2020 to present

Installation and fitting

This is a true plug-and-play replacement for the OE primary catalyst, reusing original mounting points and sensors. For professional fitting, heat cycle checks and aftercare, book with MJ Modifications in Warwickshire. Request a fitting quote at info@mjmodifications.co.uk.

Engineering highlights

Each application is reverse engineered by 3D scanning the factory part to capture precise geometry. Flow, pressure and thermal behaviour are then simulated to optimise diameter and bend radii. Manufacturing uses a 7-axis CNC bender to maintain tube roundness, followed by direct spot welding and reinforced overlap TIG seams at the turbo flange and high-heat areas for maximum reliability.

Warranty

Stone Exhaust 2 year warranty.

Manufacturer

Stone Exhaust

Video

BMW G29 B58D Z4 M40i - Stone Eddy Catted Front Pipe

Buy with confidence from MJ Modifications

We supply, install and support Stone Exhaust products across BMW B58D platforms and the Toyota GR Supra A90. If you want OE-level fit, emissions-friendly performance and a CEL-free experience, this is the upgrade to choose. For availability and workshop booking, email info@mjmodifications.co.uk.

Part Number: A223E

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