Stone Exhaust BMW B46 Catless Downpipe (Non-OPF) - Decat Turbo Downpipe, Stainless - 230i 330i 430i 520i 530i - F22 F23 F30 F31 F34 F32 F33 F36 G30 G01 X3 G02 X4 - A224P

Stone Exhaust De-Cat Front Pipe for BMW 2.0 B46 Petrol Turbo - Non OPF

Unlock faster spool, crisper throttle response and a richer exhaust tone from your BMW four-cylinder 2.0 turbo. This Stone Exhaust cat delete front section is engineered specifically for the B46 petrol engine without a particulate filter, delivering a free-flow route straight off the turbine for maximum efficiency and a proper motorsport soundtrack.

Perfect for enthusiasts who want a high-flow turbo outlet on 230i, 330i, 430i, 520i and 530i models plus selected X3 and X4 variants, this race-only front pipe keeps factory-style fitment while dramatically reducing restriction compared to the OE catalyst.

Highlights

• De-cat turbo front pipe for BMW B46 2.0T petrol engines without OPF or GPF
• One-piece mandrel-bent stainless construction for smooth, high-velocity gas flow
• Integrated flex section to absorb thermal movement and lessen stress on joints
• Reinforced turbine flange with crisscross and overlapping welds for durability under heat
• Mechanised welding arms for consistent, precise weld penetration
• 3D scanning and reverse engineered routing to maintain clearances and OE-style fit
• 7-axis CNC bends with up to 98 percent roundness and under 0.025 mm tolerance
• Direct replacement of the stock catalyst section - designed for straightforward installation

What you will notice

• Lower back pressure for more efficient turbo operation
• Quicker boost build and sharper pedal response
• Deeper, more purposeful exhaust note on the B46 2.0 turbo
• High-quality fabrication aimed at fast-road and track reliability

We have installed and supplied these Stone Exhaust systems for our customers and feedback has been consistently positive on fit, finish, weld quality, sound and drivability gains.

Engineering detail

Stone Exhaust uses state-of-the-art 3D flow measurement and reverse engineering of OEM components to create a one-piece, mandrel-formed path that minimises turbulence. Mechanical welding arms ensure no weld intrusion into the gas stream, helping maintain velocity and consistent performance. The result is a high-efficiency de-cat front section that supports turbine efficiency and repeatable, OEM-like fitment across B46 applications.

7-axis CNC bending delivers excellent roundness even at tight radii, helping avoid deformation that can disturb flow or concentrate stress. Combined with reinforced flange welding and a robust flex section, this assembly is built to tolerate the thermal demands of the B46 turbocharged platform.

Vehicle applications - B46 petrol without OPF

BMW 2 Series

• F22 230i and 230i xDrive (2015+)
• F22 LCI 230i (2017+) and 230i xDrive (2016+)
• F23 230i and 230i xDrive (2015+)
• F23 LCI 230i (2017+) and 230i xDrive (2016+)

BMW 3 Series

• F30 LCI 330i (2014+)
• F31 LCI 330i xDrive (2015+)
• F34 GT LCI 330i xDrive (2015+)

BMW 4 Series

• F32 LCI 430i and 430i xDrive (2016+)
• F33 LCI 420i, 430i and 430i xDrive (2016+)
• F36 LCI 420i, 420i xDrive and 430i (2016+)

BMW 5 Series

• G30 520i (2018+)
• G30 530i and 530i xDrive (2015+)

BMW X Series

• G01 X3 20i xDrive (2017-2018) and X3 30i xDrive (2016-2018)
• G02 X4 20i xDrive (2017-2019) and X4 30i xDrive (2017-2019)

For non-OPF vehicles only. Please check your car’s specification and the compatibility list before ordering.

Part number

A224P

Installation and support

Professional fitting recommended. MJ Modifications offers installation at our Warwickshire workshop. To request a quote or confirm compatibility, email info@mjmodifications.co.uk.

Warranty

Stone Exhaust 2-year warranty.

Usage notice

De-cat exhaust components are intended for motorsport or off-road use where permitted. Regulations on emissions and aftermarket parts vary by region. Please ensure compliance with local laws before purchase and installation.

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