{"product_id":"stone-exhaust-bmw-n20-f30-f32-cat-back-valvetronic-exhaust-inc-328i-428i-1","title":"Stone Exhaust Valved Cat-Back Exhaust for BMW N20 F30 F32 F33 F36 (328i 428i) OEM Integrated Valve, Quad\/Dual\/Single Exit UK","description":"\u003cdiv\u003e\n  \u003ch2\u003eStone Exhaust Switchable Catback for BMW F30 F32 F33 F36 328i 428i, UK supplied\u003c\/h2\u003e\n\n  \u003cp\u003eTransform the character of your BMW N20-powered 3 and 4 Series with Stone’s valve-controlled rear system. This premium, direct-fit upgrade delivers a richer tone on throttle and refined cabin manners on a cruise, with seamless plug-in operation using the factory flap control. If you are searching for a sports exhaust for 328i, a switchable flap system for 428i, a performance back box for F30 or F32, quad tip conversion for 4 Series, or a dual exit setup for xDrive models, this is the high quality choice for UK enthusiasts.\u003c\/p\u003e\n\n  \u003ch3\u003eKey reasons enthusiasts choose Stone\u003c\/h3\u003e\n  \u003cul\u003e\n    \u003cli\u003eFactory flap integration uses the car’s ECU to manage the valve for everyday refinement and a more aggressive note when you want it.\u003c\/li\u003e\n    \u003cli\u003eOptional Stone Valvetronic System Single Valve upgrade for remote flap control via a simple plug in OBDII controller.\u003c\/li\u003e\n    \u003cli\u003eOne piece construction for strength, consistent flow and precise alignment.\u003c\/li\u003e\n    \u003cli\u003e3D scanned and reverse engineered from the original system for genuine bolt-on fitment and perfect tip placement.\u003c\/li\u003e\n    \u003cli\u003eDeveloped on the dyno to optimise gas speed and deliver that signature Stone tone without motorway drone.\u003c\/li\u003e\n    \u003cli\u003e7 axis CNC mandrel bending maintains roundness through tight radii to reduce turbulence.\u003c\/li\u003e\n    \u003cli\u003eAdvanced welding techniques, including crisscross and overlapping in high heat zones, for durability under sustained load.\u003c\/li\u003e\n    \u003cli\u003eAutomated spot welding ensures consistent penetration and a clean, premium finish.\u003c\/li\u003e\n    \u003cli\u003eIn house R\u0026amp;D focusing on flow, temperature management and back pressure balance.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003ch3\u003eHow the factory-controlled flap behaves\u003c\/h3\u003e\n  \u003cp\u003eThe integrated valve works with your car’s electronics, keeping things civilised at light throttle then opening to unlock a deeper, sportier soundtrack as you push on. Want manual control at any time? Add the Stone Valvetronic System Single Valve for remote operation using the plug and play OBDII controller.\u003c\/p\u003e\n\n  \u003ch3\u003eThe sound and response upgrade your BMW deserves\u003c\/h3\u003e\n  \u003cp\u003eExpect a deeper idle, sharper response and a crisp, motorsport-inspired note under load, all without the intrusive cabin boom that spoils long journeys. Ideal for daily use, weekend drives and show car builds with quad tips.\u003c\/p\u003e\n\n  \u003ch3\u003eCompatibility, N20 2.0 turbo models\u003c\/h3\u003e\n  \u003cp\u003eBMW 3 Series\u003c\/p\u003e\n  \u003cul\u003e\n    \u003cli\u003eF30 328i, 2011 onwards\u003c\/li\u003e\n  \u003c\/ul\u003e\n  \u003cp\u003eBMW 4 Series\u003c\/p\u003e\n  \u003cul\u003e\n    \u003cli\u003eF32 428i and 428i xDrive, 2012 onwards\u003c\/li\u003e\n    \u003cli\u003eF33 428i and 428i xDrive, 2013 onwards\u003c\/li\u003e\n    \u003cli\u003eF36 428i and 428i xDrive, 2013 onwards\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003ch3\u003eOptions and part numbers\u003c\/h3\u003e\n  \u003cul\u003e\n    \u003cli\u003eAP501, single left exit with twin tailpipes\u003c\/li\u003e\n    \u003cli\u003eAP512, dual exit with single tailpipe each side\u003c\/li\u003e\n    \u003cli\u003eAP512Q, dual exit with quad tailpipes\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003ch3\u003eIn the metal\u003c\/h3\u003e\n  \u003cp\u003eInstalled examples of the Stone system on N20 F30 F32 F33 F36:\u003c\/p\u003e\n  \u003cp\u003e\n    \u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0284\/6300\/5795\/files\/Untitled_826b0f54-3098-4016-a70e-08d0ad91eb69_600x600.png?v=1588851543\" alt=\"BMW F30 F32 N20 Stone switchable catback dual exit quad tips fitted UK\"\u003e\n  \u003c\/p\u003e\n  \u003cp\u003e\n    \u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0284\/6300\/5795\/files\/Untitled1_12e09e33-782b-4489-83be-55e14fcd1b2b_600x600.png?v=1588851554\" alt=\"BMW 328i 428i Stone rear section system UK retailer\"\u003e\n  \u003c\/p\u003e\n  \u003cp\u003e\n    \u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0284\/6300\/5795\/files\/Untitled2_c23d2407-3ac1-4c70-a4a3-c1096e5563c2_600x600.png?v=1588851562\" alt=\"F30 F32 quad tip conversion Stone Exhaust\"\u003e\n  \u003c\/p\u003e\n  \u003cp\u003e\n    \u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0284\/6300\/5795\/files\/Untitled3_838ccc82-7e14-4b0c-a505-216e47e9a94b_600x600.png?v=1588851570\" alt=\"Stone ECU controlled flap catback for BMW N20 UK\"\u003e\n  \u003c\/p\u003e\n\n  \u003ch3\u003eEngineering detail\u003c\/h3\u003e\n  \u003cp\u003eStone engineers 3D scan the original components to map diameters, routing and bend angles, then simulate flow, heat and pressure to refine performance and fit to within 0.025 mm.\u003c\/p\u003e\n  \u003cp\u003e\n    \u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0284\/6300\/5795\/files\/1_9336c8b0-c9ea-4822-891c-83490f630707.jpg?v=1572705528\" alt=\"Stone Exhaust 3D scanning and reverse engineering\"\u003e\n  \u003c\/p\u003e\n  \u003cp\u003e7 axis CNC bending preserves up to 98 percent roundness through tight bends, keeping gas speed high and welds stress free. High heat areas receive crisscross and overlapping welds, while automated spot welding adds consistency and strength.\u003c\/p\u003e\n  \u003cp\u003e\n    \u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0284\/6300\/5795\/files\/bending.jpg?v=1572739395\" alt=\"Precision CNC mandrel bending Stone Exhaust\"\u003e\n  \u003c\/p\u003e\n  \u003cp\u003e\n    \u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0284\/6300\/5795\/files\/Stone_Exhaust_Art_of_Welding_-_1_1024x1024.jpg?v=1572828150\" alt=\"Stone Exhaust TIG welding detail\"\u003e\n  \u003c\/p\u003e\n  \u003cp\u003e\n    \u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0284\/6300\/5795\/files\/Stone_Exhaust_Art_of_Welding_-_2_1024x1024.jpg?v=1572828178\" alt=\"Stone Exhaust spot welding quality\"\u003e\n  \u003c\/p\u003e\n\n  \u003ch3\u003eWhat owners say\u003c\/h3\u003e\n  \u003cp\u003eWe have fitted and tested these systems in house and feedback has been excellent. Customers love the perfect alignment, premium build, deeper soundtrack and the lack of motorway boom. It is the sound your F30 328i or F32 428i should have had from the factory.\u003c\/p\u003e\n\n  \u003ch3\u003eFitting and installation\u003c\/h3\u003e\n  \u003cp\u003eProfessional installation recommended. MJ Modifications, based in Warwickshire, can fit this system. Request a quote at \u003ca href=\"mailto:info@mjmodifications.co.uk\"\u003einfo@mjmodifications.co.uk\u003c\/a\u003e.\u003c\/p\u003e\n\n  \u003ch3\u003eWarranty\u003c\/h3\u003e\n  \u003cp\u003eStone Exhaust 2 year warranty.\u003c\/p\u003e\n\n  \u003ch3\u003eSearch-friendly terms customers use\u003c\/h3\u003e\n  \u003cp\u003eBMW F30 328i sports exhaust UK, BMW F32 428i switchable flap exhaust, BMW F33 convertible performance exhaust, BMW F36 Gran Coupe quad tip exhaust, BMW N20B20 turbo exhaust upgrade, 3 Series 328i back box UK, 4 Series 428i muffler upgrade, ECU controlled flap system BMW, BMW 428i xDrive dual exit exhaust, BMW 328i quad tip conversion, F30 rear section upgrade, F32 tailpipe upgrade, Stone Exhaust UK dealer, plug in OBD valve controller, drone free catback BMW, performance exhaust for BMW 2.0 turbo, bolt on catback for F30 F32, UK BMW tuning parts, quad tips for 4 Series, dual exit for 3 Series.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"Stone Exhaust","offers":[{"title":"OEM Integrated Valve(s) \/ Single Exit (Left) with Twin Tailpipes (Require Original Bumper) \/ Flat Cut Gloss Carbon Fibre (82mm)","offer_id":55977892053378,"sku":null,"price":2396.16,"currency_code":"GBP","in_stock":true},{"title":"OEM Integrated Valve(s) \/ Dual Exit with Single Tailpipe (Require 335i\/435i Bumper) \/ Flat Cut Gloss Carbon Fibre (82mm)","offer_id":55977892086146,"sku":null,"price":2396.16,"currency_code":"GBP","in_stock":true},{"title":"OEM Integrated Valve(s) \/ Dual Exit with Quad Tailpipes (Require M Performance Bumper) \/ Flat Cut Gloss Carbon Fibre (82mm)","offer_id":55977892118914,"sku":null,"price":2835.84,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0871\/5445\/8937\/files\/BMWN20F30F32_Cat-BackValvetronicExhaust2-2_1024x1024_2x_36a12ae2-25cd-4335-b183-d37d9ea4969f.webp?v=1763377188","url":"https:\/\/mjmodifications.co.uk\/products\/stone-exhaust-bmw-n20-f30-f32-cat-back-valvetronic-exhaust-inc-328i-428i-1","provider":"MJ Modifications","version":"1.0","type":"link"}