{"product_id":"stone-exhaust-bmw-b58d-g20-g21-cat-back-valvetronic-exhaust-system-gpf-m340i-m340i-xdrive","title":"Stone Exhaust B58 Switchable Valved Cat-Back Performance Exhaust System (Catback) for BMW 3 Series G20\/G21 M340i\/M340i xDrive \u0026 4 Series G22\/G23\/G26 M440i\/M440i xDrive - OPF\/GPF Compatible, Active Valve OEM Control, No Drone | AP546A","description":"\u003cdiv class=\"product__description rte\"\u003e\n  \u003ch2\u003eBMW B58 G20 G21 G22 G23 G26 Switchable Sports Exhaust - OPF and GPF Compatible - Stone AP546A\u003c\/h2\u003e\n\n  \u003cp\u003eGive your 3 Series or 4 Series the soundtrack it should have. This Stone AP546A switchable sports system integrates with the factory flap motors on OPF and GPF cars, delivering a richer, deeper note when you want excitement and refined quiet when you do not. Designed specifically for the B58 platform on M340i and M440i models, it offers superb fitment, clean pipe routing and tangible performance benefits proven on Stone's in-house dyno.\u003c\/p\u003e\n\n  \u003cp\u003eIf you are hunting for a BMW M340i or M440i upgrade that keeps factory drive modes intact while unlocking a motorsport-inspired tone with zero motorway boom, this is the plug-and-play solution that enthusiasts choose.\u003c\/p\u003e\n\n  \u003ch3\u003eWhy this system stands out\u003c\/h3\u003e\n  \u003cul\u003e\n    \u003cli\u003eFactory valve motor integration - uses the original actuators for seamless Comfort to Sport transitions.\u003c\/li\u003e\n    \u003cli\u003ePrecise OE-style fit - developed from detailed 3D scans for accurate alignment on OPF and GPF cars.\u003c\/li\u003e\n    \u003cli\u003eRefined with valves closed, beefy and aggressive with valves open - without the annoying cabin resonance many systems suffer from.\u003c\/li\u003e\n    \u003cli\u003eIn-house development and dyno validation by Stone for real, repeatable gains and consistent quality.\u003c\/li\u003e\n    \u003cli\u003eOptional Stone Valvetronic controller adds remote control and rpm-based auto open functionality via a simple OBDII plug-in.\u003c\/li\u003e\n    \u003cli\u003eOne-piece layout with precision machine welding for strength and lasting durability.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003ch3\u003eValve control options\u003c\/h3\u003e\n  \u003cul\u003e\n    \u003cli\u003e\n\u003cstrong\u003eFactory flap control:\u003c\/strong\u003e Retains ECU-managed valve operation. All standard drive modes work exactly as they should.\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eOptional Stone Valvetronic (dual valves):\u003c\/strong\u003e Handheld remote to open or close at will, plus Auto Mode that opens at a chosen engine speed. Fast, plug-and-play OBDII install.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003ch3\u003eOPF and GPF friendly\u003c\/h3\u003e\n  \u003cp\u003eRunning a particulate filter. Stone provides an OPF solution that can be supplied free of charge, allowing trouble-free installation on filter-equipped cars without warning lights. No ECU coding required to suppress OPF messages.\u003c\/p\u003e\n\n  \u003ch3\u003eEngineering detail\u003c\/h3\u003e\n  \u003cul\u003e\n    \u003cli\u003e\n\u003cstrong\u003e3D scanned development:\u003c\/strong\u003e OEM system mapped for optimised routing, diameters and bends.\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003e7-axis CNC bending:\u003c\/strong\u003e Up to 98 percent roundness at tight 180 degree bends to protect flow and strength.\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eUltra-precise fabrication:\u003c\/strong\u003e Integrally moulded pipework with sub-0.025 mm accuracy helps minimise turbulence.\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eAdvanced weld techniques:\u003c\/strong\u003e Crisscross and overlapping welds at stress points with direct spot welding for accuracy and durability.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003ch3\u003eVehicle coverage\u003c\/h3\u003e\n  \u003cp\u003e\u003cstrong\u003eEngine:\u003c\/strong\u003e BMW B58\u003c\/p\u003e\n  \u003cp\u003e\u003cstrong\u003eBMW 3 Series\u003c\/strong\u003e\u003c\/p\u003e\n  \u003cul\u003e\n    \u003cli\u003eG20 M340i and M340i xDrive (2018-2020)\u003c\/li\u003e\n    \u003cli\u003eG21 M340i xDrive (2018-2020)\u003c\/li\u003e\n  \u003c\/ul\u003e\n  \u003cp\u003e\u003cstrong\u003eBMW 4 Series\u003c\/strong\u003e\u003c\/p\u003e\n  \u003cul\u003e\n    \u003cli\u003eG22 M440i and M440i xDrive (2020+)\u003c\/li\u003e\n    \u003cli\u003eG23 M440i xDrive (2020+)\u003c\/li\u003e\n    \u003cli\u003eG26 M440i xDrive (2020+)\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003ch3\u003ePart number\u003c\/h3\u003e\n  \u003cp\u003e\u003cstrong\u003eAP546A\u003c\/strong\u003e\u003c\/p\u003e\n\n  \u003ch3\u003eWarranty\u003c\/h3\u003e\n  \u003cp\u003eStone Exhaust 2-year warranty.\u003c\/p\u003e\n\n  \u003ch3\u003eInstallation and fitting\u003c\/h3\u003e\n  \u003cp\u003eThis is a direct-fit system designed to work with the original valve motors. For a professional install, book with MJ Modifications in Warwickshire. Request a fitting quote at \u003ca href=\"mailto:info@mjmodifications.co.uk\"\u003einfo@mjmodifications.co.uk\u003c\/a\u003e.\u003c\/p\u003e\n\n  \u003ch3\u003eReal-world feedback\u003c\/h3\u003e\n  \u003cp\u003eWe run Stone systems on our own B58 cars and have fitted them for many customers. The verdict is consistent: perfect OE-style fitment, a tasteful tone with the valves shut, a strong, sporty soundtrack with the valves open and no drone on long journeys.\u003c\/p\u003e\n\n  \u003ch3\u003eCommon searches for this upgrade\u003c\/h3\u003e\n  \u003cp\u003eBMW B58 sports exhaust, M340i switchable exhaust, M440i valve controlled exhaust, G20 GPF compatible exhaust, G21 performance system, G22 xDrive exhaust upgrade, G23 active valve exhaust, G26 performance cat back, BMW M Performance style exhaust alternative, B58 turbo sound upgrade, UK BMW exhaust specialist, Warwickshire BMW exhaust fitting, catback for M340i, cat back for M440i, BMW flap controlled exhaust, best exhaust for B58 UK, OPF friendly exhaust BMW, GPF solution BMW, OBD2 valve controller BMW.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"Stone Exhaust","offers":[{"title":"Default Title","offer_id":55978558587266,"sku":null,"price":2741.76,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0871\/5445\/8937\/files\/WhatsAppImage2023-04-20at2.20.09PM_42f2b9a7-2ed1-4721-9011-ecc0c8e3662a.jpg?v=1763379761","url":"https:\/\/mjmodifications.co.uk\/products\/stone-exhaust-bmw-b58d-g20-g21-cat-back-valvetronic-exhaust-system-gpf-m340i-m340i-xdrive","provider":"MJ Modifications","version":"1.0","type":"link"}