{"product_id":"stone-exhaust-bmw-s58-g80-m3-g82-g83-m4-oem-integrated-valved-catback-exhaust-system","title":"Stone Exhaust G8X S58 Active Valved Cat-Back (Cat Back\/Catback) for BMW G80 M3\/M3 Competition \u0026 G82\/G83 M4\/M4 Competition | Switchable OEM Valve Control, No-Drone Performance Exhaust, Valvetronic Remote Ready | 2020+ | AP554Q","description":"\u003cdiv class=\"product__description rte\"\u003e\n  \u003ch2\u003eStone Exhaust switchable sports system for BMW G8X S58 platform with factory flap control\u003c\/h2\u003e\n  \n  \u003cp\u003e\n    Give your G8X the soundtrack it deserves. This Stone Exhaust cat-back upgrade transforms the aural character and throttle feel of the S58 twin turbo while keeping day-to-day manners intact. It integrates with the car’s original valve actuators, so Comfort, Sport and Sport Plus behave exactly as they should. Quiet when you want it, fierce when you don’t.\n  \u003c\/p\u003e\n  \n  \u003cp\u003e\n    Developed using full 3D scanning, reverse engineering and in-house dyno refinement, the Stone system delivers a rich tone, crisp cold starts and clean, drone-free cruising. We have fitted this setup on customer cars and our own demonstrators, and feedback has been outstanding for both sound quality and precision fit.\n  \u003c\/p\u003e\n  \n  \u003ch3\u003eReasons enthusiasts choose this upgrade\u003c\/h3\u003e\n  \u003cul\u003e\n    \u003cli\u003eFactory flap integration for seamless drive mode behaviour with ECU-managed valves\u003c\/li\u003e\n    \u003cli\u003eOptional Stone Valvetronic remote kit with plug-in OBD controller for manual open or closed control\u003c\/li\u003e\n    \u003cli\u003eOne-piece construction with machine-true welds for alignment and durability\u003c\/li\u003e\n    \u003cli\u003eScanned from the original system for exact, direct-fit installation\u003c\/li\u003e\n    \u003cli\u003eDyno-developed flow and tone with a deep, motorsport-inspired character\u003c\/li\u003e\n    \u003cli\u003eRefined on the motorway with no intrusive cabin resonance\u003c\/li\u003e\n    \u003cli\u003ePart number: \u003cstrong\u003eAP554Q\u003c\/strong\u003e\n\u003c\/li\u003e\n  \u003c\/ul\u003e\n  \n  \u003ch3\u003eEngineered for the S58\u003c\/h3\u003e\n  \u003cp\u003e\n    Stone’s R\u0026amp;D focuses on gas velocity and acoustic tuning specifically for the S58 found in the latest M3 and M4. Precision 7-axis CNC bend forming maintains up to 98 percent roundness for consistent flow. Crisscross and overlapping weld techniques, direct spot welding and tight QC deliver a finish that looks as good as it sounds.\n  \u003c\/p\u003e\n  \n  \u003ch3\u003eOEM flaps vs Valvetronic remote\u003c\/h3\u003e\n  \u003cul\u003e\n    \u003cli\u003eFactory flap control: behaves like stock via the car’s ECU and drive modes\u003c\/li\u003e\n    \u003cli\u003eValvetronic remote upgrade: dual valves controlled by Stone’s handheld remote through a simple OBD plug, so you choose quiet or loud on demand\u003c\/li\u003e\n  \u003c\/ul\u003e\n  \n  \u003ch3\u003eVehicle compatibility\u003c\/h3\u003e\n  \u003cp\u003eBMW M models with the S58 engine:\u003c\/p\u003e\n  \u003cul\u003e\n    \u003cli\u003eG80 M3 and M3 Competition, 2020 onwards\u003c\/li\u003e\n    \u003cli\u003eG82 M4 and M4 Competition, 2020 onwards\u003c\/li\u003e\n    \u003cli\u003eG83 M4 Convertible and M4 Competition Convertible, 2020 onwards\u003c\/li\u003e\n  \u003c\/ul\u003e\n  \n  \u003ch3\u003eFitting and support\u003c\/h3\u003e\n  \u003cp\u003e\n    Professional installation recommended. MJ Modifications offers in-house fitting at our Warwickshire workshop. Request a quote: \u003ca href=\"mailto:info@mjmodifications.co.uk\"\u003einfo@mjmodifications.co.uk\u003c\/a\u003e.\n  \u003c\/p\u003e\n  \n  \u003ch3\u003eCompatibility check before dispatch\u003c\/h3\u003e\n  \u003cp\u003e\n    We verify your vehicle before shipping. Please provide your UK registration or the last 7 digits of your VIN at checkout so we can confirm suitability for your car.\n  \u003c\/p\u003e\n  \n  \u003ch3\u003eManufactured by\u003c\/h3\u003e\n  \u003cp\u003eStone Exhaust\u003c\/p\u003e\n  \n  \u003ch3\u003eTechnical development highlights\u003c\/h3\u003e\n  \u003cul\u003e\n    \u003cli\u003eFull 3D scan and reverse engineering of the original G8X system\u003c\/li\u003e\n    \u003cli\u003e7-axis CNC bending for accurate pipe geometry and consistent flow\u003c\/li\u003e\n    \u003cli\u003eCrisscross and overlapping welds for strength in high heat areas\u003c\/li\u003e\n    \u003cli\u003eDirect spot welding with mechanical arms for consistent penetration and finish\u003c\/li\u003e\n    \u003cli\u003eIntegrally formed sections for accuracy and leak-free performance\u003c\/li\u003e\n  \u003c\/ul\u003e\n  \n  \u003ch3\u003eMedia\u003c\/h3\u003e\n  \u003cp\u003e\n    \u003cimg alt=\"Stone Exhaust for BMW G8X S58 cat-back installed on M4\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0284\/6300\/5795\/files\/BMW_G82_S58_M4C_EC_8_1024x1024.jpg?v=1651079063\"\u003e\n  \u003c\/p\u003e\n  \u003cp\u003e\n    \u003cimg alt=\"Stone Exhaust G8X S58 cat-back close-up detail\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0284\/6300\/5795\/files\/BMW_G82_S58_M4C_EC_5_1024x1024.jpg?v=1651079069\"\u003e\n  \u003c\/p\u003e\n  \u003cp\u003e\n    \u003ciframe title=\"Stone Exhaust G8X S58 Cat-Back Sound\" width=\"1182\" height=\"665\" src=\"https:\/\/www.youtube.com\/embed\/sLIePESmk1s\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture\" allowfullscreen\u003e\u003c\/iframe\u003e\n  \u003c\/p\u003e\n  \n  \u003ch3\u003eSearch terms customers use\u003c\/h3\u003e\n  \u003cp\u003e\n    G8X switchable exhaust. S58 sports system. G80 saloon performance exhaust. G82 coupe exhaust upgrade. G83 convertible exhaust upgrade. M3 Competition flap control exhaust. M4 Competition valve control exhaust. Cat-back kit for G80. Cat back for G82. Plug-in OBD valve controller. Remote valve exhaust for M3 M4. G8X exhaust with no drone. UK installation Warwickshire. BMW S58 exhaust upgrade 2020 on.\n  \u003c\/p\u003e\n\u003c\/div\u003e","brand":"Stone Exhaust","offers":[{"title":"OEM Integrated Valves \/ Flat Cut Gloss Carbon Fiber (82mm)","offer_id":56008722186626,"sku":null,"price":3841.92,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0871\/5445\/8937\/files\/StoneExhaust_1946x_0f04c62a-b8fb-49e4-b8d7-4ee2bad02b5f.png?v=1764091346","url":"https:\/\/mjmodifications.co.uk\/products\/stone-exhaust-bmw-s58-g80-m3-g82-g83-m4-oem-integrated-valved-catback-exhaust-system","provider":"MJ Modifications","version":"1.0","type":"link"}