Stone Exhaust A223P B58D OPF/GPF Delete Catless Downpipe De-Cat Turbo Front Pipe for Toyota GR Supra A90 3.0, BMW 3 Series G20/G21 M340i xDrive, Z4 M40i G29 – Primary Cat Delete/Race Pipe

Stone Exhaust B58D OPF GPF De-cat Front Pipe for GR Supra A90, BMW 3 Series G20 G21 340i and Z4 G29 M40i — Part Number A223P

Unlock serious flow and sound on OPF equipped B58D cars with Stone Exhaust’s A223P turbo front pipe. This high flow de-cat pipe replaces the primary catalyst on Euro 6 particulate filter variants, releasing sharper throttle response, quicker turbo spool and a deeper, motorsport tone while retaining a straight bolt-on install to the factory turbo and stock system. Perfect upgrade for Toyota Supra MK5 A90 3.0, BMW M340i G20 G21 including xDrive, and BMW Z4 M40i G29 running the B58D with GPF.

We fit these in-house at MJ Modifications and run Stone hardware on our own B58 projects. Fitment is spot on, weld quality is superb and customer satisfaction has been consistently excellent. If you are hunting for a Supra A90 de-cat pipe, 340i G20 race down pipe, M340i xDrive turbo outlet or Z4 M40i G29 straight-through front pipe for OPF cars, this is the premium solution.

Why choose this A223P de-cat front pipe

• Designed specifically for B58D OPF GPF variants for maximum gas velocity and reduced back pressure
• Direct fit to OE turbo housing and factory exhaust — no cutting, no additional fabrication
• Distinct flex section helps absorb heat expansion and vibration to minimise fatigue
• Reinforced turbo flange with crisscross welds for durability under high load
• Smooth, one piece bends for uninterrupted flow and minimal turbulence
• Robotic welding for precise, repeatable build quality
• 3D scanned and reverse engineered from OEM parts for an exact factory-style install
• Backed by a 2 year manufacturer warranty from Stone Exhaust

Engineered for OPF-equipped B58D

Stone Exhaust developed the A223P using full reverse engineering of the Euro-spec B58D exhaust path. OEM components were 3D scanned to define optimal tube diameter, routing and bend geometry around the GPF layout seen on Supra A90, M340i and Z4 platforms. Computational analysis including flow modelling and thermal review was used to refine the path for real-world gains on OPF cars, delivering a responsive, freer-revving feel and a purposeful soundtrack.

Build quality you can trust

• Multi-axis CNC bending for consistent roundness and smooth radii
• Deep penetration robotic welds with overlapping techniques at high temperature joints
• Minimal internal weld disturbance for clean exhaust gas transition

The result is a high flow turbo pipe that installs like factory, withstands heat and abuse, and transforms the character of your B58D OPF vehicle.

Compatibility

Engine B58D with OPF GPF

Toyota

• GR Supra A90 3.0 B58D with OPF GPF

BMW

• 3 Series G20 M340i and M340i xDrive B58D with OPF GPF
• 3 Series Touring G21 M340i xDrive B58D with OPF GPF
• Z4 G29 M40i B58D with OPF GPF

Part number and warranty

Part number A223P

Brand Stone Exhaust

Warranty 2 Years manufacturer warranty

Fitting and support

Professional installation recommended. MJ Modifications offers in-house fitting in Warwickshire. Request a fitted quote at info@mjmodifications.co.uk.

Search terms to help you find the right upgrade

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For off road or motorsport use only where local laws permit.