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Stone Exhaust BMW B48D G20 G21 Eddy Catalytic Downpipe (Inc. 320, 330i / OPF Model) | Stone Exhaust USA
Stone Exhaust BMW B48D G20 G21 Eddy Catalytic Downpipe (Inc. 320, 330i / OPF Model) | Stone Exhaust USA
Stone Exhaust BMW B48D G20 G21 Eddy Catalytic Downpipe (Inc. 320, 330i / OPF Model) | Stone Exhaust USA
Stone Exhaust BMW B48D G20 G21 Eddy Catalytic Downpipe (Inc. 320, 330i / OPF Model) | Stone Exhaust USA
Stone Exhaust BMW B48D G20 G21 Eddy Catalytic Downpipe (Inc. 320, 330i / OPF Model) | Stone Exhaust USA

Stone Exhaust BMW B48D G20 G21 G22 G23 Eddy Catalytic Downpipe (Inc. 320, 330i, 420i & 430i / OPF Model)

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Meet the latest patented technology that adheres to the world's increasingly stringent environmental regulations, at the same time enhances performance to another level on your BMW G20, G21, G22 & G23 320, 330i, 420i & 430i. In comparison to commercially available linear frustums, the "eddy catalytic technology" adopts an arc-packaging method. The turbine emissions process produces a vortex effect which purifies the exhaust gases while maintaining an equal amount of back pressure. When compared to a variety of conventional straight downpipes, the patented eddy catalytic technology can effectively increase horsepower and torque. In the lower rpm you will be immerse with vast amount of torque until you reach higher rpm where the vortex effect really comes to life and opens up the Catalytic, resulting in a performance similar to a 100 CELL Catalytic. However in the lower rpm, the catalytic will produce efficient and clean emission similar to a 400CEL Catalytic and produce no Check Engine Lights, completely error free.



  • Patented O2 sensor technology design provides real-time data performance by accurately sensing every rotating displacement.
  • No more delayed in power delivery
  • Using one of the rare noble metal to help efficiently filter out exhaust gas.
  • Computer simulation to obtain the best diameter.
  • Special 3D design to achieve 100% OEM fitment, no modification required.
  • SUS304 Premium Grade Stainless steel.
  • Dual Cross-Welding Technology providing substantial increase durability at the turbo Flange.


    R&D and 3D Scanning

    Stone Exhaust engineers use reverse engineering by 3D scanning OEM parts to understand their functionality and identify weaknesses. Data has been collected continuously in order to analyze factors such as pipe diameter, route and degrees of the bending angles of the B48D Exhaust System found on the BMW G20, G21, G22 & G23 320, 330i, 420i & 430i. 

    During R&D, Stone Exhaust utilizes the 3D simulation software to stimulate the exhaust gas flow movement, thermal and pressure rise zone. Progressive improvements were continually made until the optimal performance was achieved.

    Stone Exhaust System 3D Scanning Reverse Engineering UK


    7 Axis CNC Bending Machine

    Stone Exhaust System are constructed utilizing a 7 axis CNC Bending Machine which is the ultimate machine for high levels of precision delivery, necessary for industries such as the aerospace and defense industries.

      With the state-of-the-art bending machine, Stone Exhaust has achieved the industry’s standard to an impressive 98% roundness, whilst maintaining the wear of the outer bore at only 25% at 180°. Airflow obstruction and welding fracture problems are prevented by utilizing this technology. With the combination of the CNC Bending machine, Reverse Engineering and 3D Design Scanning, Stone exhaust has created an integrally molded exhaust pipe with an accuracy error under 0.025mm.

       7 Axis CNC Bending Machine | Stone Exhaust USA


      Crisscross and Overlapping Welding Technique

      The flange between the turbo and the downpipes reaches extreme temperatures (800℃ to 1100℃) which creates stress on the connection point. By utilizing both welding techniques to increases the width and penetration of welds. This increases the endurance and tolerance of these connection points, leading to quality products with reliable performance.

      Stone Exhaust Art of Welding - Stone Exhaust USA


      Direct Spot Welding

      Our highly skilled engineers perform direct spot welding to increase product strength. This is undertaken by mechanical welding arms, proven to achieve greater precision and penetration in their welds compared to manual welding, resulting in an end product that is a work of art.

      Stone Exhaust Art of Welding - Stone Exhaust USA


      Art of Welding

      Art of Welding | Stone Exhaust USA


      Compatibility - B48D Engine

        BMW Z Series

        • G29 Z4 20/30i (2019+)

        BMW 3 Series

        • G20/G21 320i (2019+)
        • G20/G21 330i/330i xDrive (2017+)

        BMW 4 Series

        • G22 420/430i(x)  (2020+)
        • G23 420/430i(X)  (2020+)
        • G26 420/430i(x)  (2020+)





              Stone Exhaust 2 Year Warranty



              70cm x 20cm x 18cm 



              4.16 kg 


              Emission Notice 

              Various U.S. states and the U.S. federal government have individual laws regulating the use of aftermarket exhaust parts and system, especially when the stock system is modified, remove, or if you are replacing original catalysts. Please consult the appropriate law department in your area before installing any aftermarket part or system on your vehicle to ensure compliance with all applicable laws. The purchasers are entirely responsible for informing themselves of the applicable laws where the products are to be used and to comply with those laws.