We are proud to introduce you to the state of the art Stone Exhaust Valvetronic Cat-Back Exhaust System, to enhance the performance and sound of your BMW G20 Sedan M340i & G21 Touring M340i Drive with the B58D engine, manufactured after 2018. Stone Exhaust has been developing world's best exhaust system since 1998, starting with 3D scanning and reverse engineering the OEM system, this allows the Stone engineers to design a 100% OEM fitment exhaust with precision. With their in-house dyno, your BMW exhaust system is proven to produce more power with the enhanced Stone signature exhaust sound.

The OEM Integred Valves option allows your exhuast system to operate as standard, where the onboard computer (ECU) will control the opening and closing of the valves automatically.

The Cat-Back Valvetronic System comes with a separate remote controller that gives you full control of the exhaust, allowing you to open and close the valves with a click of a button. You can also set it in auto mode for the valves to open at a certain rpm automatically. The Stone Valvetronic system is a plug and play system, and connects to your OBDII port, which can be installed within a few minutes.

You may wish to add the Stone Valvetronic System (Dual Valves) which enables you to control the valves remotely via the stone remote controller.

• OEM Integration
  
• Optional Stone Valvetronic System available
• OPF Exhaust Design
• Plug and Play OBDII controller
• One Piece Design
• Machine Welding
• In House Research and Development
• 3D Scanning & Reverse Engineering
• Dyno Developed In House

• Eliminates drone found on the standard exhaust system

OPF Delete

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 B58D Exhaust System found on the M340i & M340i xDrive. 

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.

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.

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.

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.

B58 Engine

BMW 3 Series

• G20 M340i/M340i xDrive (2018-2020)
• G21 M340i xDrive (2018-2020)

BMW 4 Series

• G22 M440i/M440i xDrive (2020+)
• G23 M440i xDrive (2020+)
• G26 M440i xDrive (2020+)

AP546A

Manufactured by

Stone Exhaust

Warranty

Stone Exhaust 2 Year Warranty