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Stone Exhaust

Stone Exhaust A218P High-Flow Catless Decat Downpipe / Turbo Outlet Front Pipe for BMW B48/B48D G20 G21 3 Series, G22 G23 G26 4 Series, G29 Z4 - OPF/GPF/PPF Friendly - 320i 330i 420i 430i 20i 30i xDrive

Stone Exhaust A218P High-Flow Catless Decat Downpipe / Turbo Outlet Front Pipe for BMW B48/B48D G20 G21 3 Series, G22 G23 G26 4 Series, G29 Z4 - OPF/GPF/PPF Friendly - 320i 330i 420i 430i 20i 30i xDrive

£930.24
£1,162.80 £930.24
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Heads-up on cancellations & returns: if you cancel an order or return an item, you won't get back 100% of what you paid. We apply a 10% restocking fee, the outbound shipping is non-refundable, and we have to pass on Shopify / PayPal payment processing fees; these aren't returned to us when we refund you. International orders also lose on exchange-rate spread in both directions. If the original packaging is damaged or missing, a reboxing charge applies. For international orders specifically, if you refuse to pay our shipping invoice or supply a prepaid label after placing the order, the same deductions apply. We're upfront about this — please be sure of your purchase before ordering.

High-Flow De-cat Front Pipe for BMW B48D Platforms – OPF GPF Compatible – Part No. A218P

Give your B48D-powered BMW the sharp throttle response, quicker boost build and rich turbo soundtrack it deserves with this race-focused de-cat front section from Stone Exhaust. Engineered for the latest BMW petrol particulate filter cars, this turbo outlet pipe replaces the restrictive factory component to improve exhaust gas velocity, reduce back pressure and deliver a more urgent, motorsport-inspired tone while retaining precise factory-style fitment.

Perfect for drivers who want a serious performance exhaust upgrade on track or closed-course use. We have installed this unit at MJ Modifications for our own vehicles and customer builds, and feedback on fit, finish, sound quality and drivability has been consistently excellent.

Key reasons enthusiasts choose this upgrade

  • Designed for BMW B48D applications across G-series models with OPF GPF systems
  • One-piece CNC-bent tubing for smooth, uninterrupted gas flow from the turbocharger outlet
  • Engineered flex joint to cope with heat cycles and vibration, helping to prevent cracking
  • Reinforced turbo flange with overlapping welds for long-term durability under high temperature
  • Precision machine and robotic welding for consistent penetration and repeatable quality
  • 3D-scanned and reverse engineered for OEM-like alignment and clearances
  • Direct bolt-on to the factory turbo and OE cat-back interface, no cutting required
  • Developed using flow velocity measurement and 3D simulation to optimise pressure, gas speed and thermal zones

R&D and manufacturing detail

Stone Exhaust uses full 3D scanning of the factory assembly to understand routing, pipe diameters and bend geometry, then iterates designs in simulation to remove restrictions and hot spots. The result is a highly efficient front pipe that improves exhaust efficiency beyond typical aftermarket offerings.

Formed on a 7‑axis CNC bending machine, the tubing maintains up to 98 percent roundness with only 25 percent outer bore wear even at 180 degree bends, helping to minimise turbulence and reduce weld stress. Direct spot welding via mechanical arms delivers accuracy within 0.025 mm, ensuring a secure seal at the turbo-to-downpipe interface where temperatures can reach approximately 800 to 1100 degrees Celsius.

Compatibility

Engine: BMW B48D petrol turbo

  • BMW 3 Series G20 G21 – 320i 2019+ and 330i 2017+ including xDrive
  • BMW 4 Series G22 G23 G26 – 420i and 430i 2020+
  • BMW Z4 G29 – 20i and 30i 2019+

Suitable for vehicles equipped with OPF GPF PPF systems.

What you can expect

  • Faster turbo spool and improved mid-range pull thanks to a freer-flowing turbo outlet
  • A deeper, more aggressive tone under load while maintaining excellent cruising refinement
  • Clean, factory-style installation with all mounting points in the right place

Part number

A218P

Brand and warranty

Manufacturer: Stone Exhaust

Warranty: 2 years from Stone Exhaust

Dimensions and weight

Dimensions: 70 cm x 20 m x 18 cm

Weight: 2.21 kg

Professional fitting

Want it installed by specialists in the UK? Book your fitment with MJ Modifications in Warwickshire. Email info@mjmodifications.co.uk for a quote and availability.

Usage and emissions notice

This product is intended for off-road, track or motorsport use where permitted. Laws vary by region regarding modification or removal of original emissions equipment. It is the purchaser's responsibility to check and comply with all applicable regulations before installation and use.

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