In order to get even better efficiency for the section of exhaust turbine, as well as to prevent multiple welding positions in the downpipe section, which generates ash in the pipe while welding, causing bad exhaust efficiency, and then generates vaper lock and thus inability to exhaust, Stone Exhaust uses a variety of smart ideas in downpipe design. The company employs flow velocity measurement software in 3D and the technique of one-piece bend pipes, along with mechanical arms which accurately welds without generating ash in the pipe wall in order to further exhaust efficiency of De-Cat downpipes. It is a perfect and effective product which has surpassed all similar products in the market.

• Catless downpipe for 120i, 220i, 320i, 328i, 420i & 428i with N20 engine.
• Unique Flex design to prevent breakage caused by extreme heat 
• Crisscross welding to strengthen turbo flange
  
• One Piece Design
• Machine Welding
• In House Research and Development
• 3D Scanning & Reverse Engineering
• 100% OEM Fitment

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 N20 Exhaust Systems.

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.

N20 Engine

BMW 1 Series 

• F20 120i (2010+)
• F20 LCI 120i (2014+) 
• F21 120i (2010+)

BMW 2 Series 

• F22 220i (2012+)/228i (2012+)/228i xDrive (2013+)
• F23 220i (2014+)

BMW 3 Series

• F30 320i/328i/328i xDrive (2011+)
• F30 LCI 320i/328i/328i xDrive (2014+)
• F31 320i (2011+)/320i xDrive (2012+)/328i (2011+)/328i xDrive (2012+)
• F31 LCI 328i xDrive (2014+)

BMW 4 Series

• F32 420i/420i xDrive (2013+)/428i/428i xDrive (2012+)
• F33 420i/428i/428i xDrive (2013+)
• F36 420i/420i xDrive/428i/428i xDrive (2013+)

A205P

Warranty

Stone Exhaust 2 Year Warranty

Fitted Photos

Video

BMW F36 N20 420i Full Exhaust Systems Sound