Stone Exhaust Valved Cat-Back Exhaust for BMW 330i 430i (B48) G20 G21 G22 G23 G26 - Switchable/Valvetronic, Active Valve OEM Actuator Plug-and-Play, xDrive & OPF/GPF Compatible - BMW 3 Series/4 Series Performance Rear Section - AP537

Stone Exhaust AP537 Valved Sports System for BMW 330i and 430i G‑Series

Unlock a richer soundtrack and sharper throttle response from your BMW 3 Series or 4 Series with the Stone Exhaust AP537 valved sports system. Designed specifically for G‑series 330i and 430i models powered by the B48 engine, this premium catback upgrade delivers a deeper tone when open, refined civility when closed and seamless plug‑in compatibility with the factory valve hardware. It is a true bolt-on performance exhaust that enhances daily driving and comes alive on spirited runs and track days, all without unwanted cabin boom.

We fit these systems in-house and run them on customer cars. Feedback is consistently excellent for fit, finish and the addictive B48 note. If you are searching for a BMW 330i sports exhaust, 430i performance system or a G‑series valved upgrade that looks OEM and sounds special, this is the one.

Key reasons to choose Stone AP537

• Direct connection to the factory flap actuator for true plug‑and‑play valve operation
• Optional Stone valve control kit with OBD plug for manual open and close plus automatic RPM‑based logic
• Carefully tuned for zero motorway drone and refined cruising
• Developed on Stone’s in‑house dyno with measurable performance improvements
• One‑piece layout for optimal flow and straightforward installation
• 3D digitised and reverse‑engineered from the stock system for precise fitment
• 7‑axis CNC mandrel bending retains up to 98 percent roundness for smooth gas velocity
• Crisscross and overlapping welds at high‑temperature zones for durability
• Robotic spot welding for consistent penetration and long‑term strength
• Free PPF/OPF delete harness supplied for particulate filter cars to prevent warning lights without ECU coding
• Compatible with rear‑wheel drive and all wheel drive variants

What you will notice

• Deeper, cleaner B48 voice with valves open and a subtle, refined tone when closed
• Smoother flow from precision‑formed pipework
• Real‑world, dyno‑validated gains with a more engaging driving experience

Recommended pairing

Frequently combined with the Stone B48 catless downpipe or Stone B48 Eddy catalytic downpipe for additional performance and sound enhancement.

Compatibility

For BMW G‑series 3 Series and 4 Series with the B48 engine:

• 3 Series G20 Saloon 330i
• 3 Series G21 Touring 330i
• 4 Series G22 Coupe 430i
• 4 Series G23 Convertible 430i
• 4 Series G26 Gran Coupe 430i
• Fits both RWD and AWD models, including particulate filter vehicles

PPF/OPF information

A complimentary harness is included to enable installation on petrol particulate filter cars without triggering error messages, so no ECU coding is required.

R&D and manufacturing

Stone digitally maps the OE system to capture diameter, bend radius and routing, then simulates gas flow and heat load before production. The result is precision pipework produced by 7‑axis CNC bending, reinforced by crisscross and overlapping welds at critical joints and robotic spot welding for repeatability.

Sound check videos

Installation and fitting

Direct bolt‑on fit with factory valve integration. Professional installation recommended. MJ Modifications offers expert fitting in Warwickshire. Request a quote at info@mjmodifications.co.uk.

Warranty

Stone Exhaust 2‑year warranty.

Part number

AP537

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