{"product_id":"stone-exhaust-bmw-n20-f30-f32-cat-back-valvetronic-exhaust-inc-320i-420i","title":"Stone Exhaust Valved Catback for BMW 3 Series F30 F31 \u0026 4 Series F32 F33 F36 320i\/420i (N","description":"\u003cdiv class=\"product-description\" style=\"line-height:1.6\"\u003e\n  \u003ch2\u003eStone Exhaust Valved Cat Back for BMW F30 F31 F32 F33 F36 320i and 420i - N20 Turbo\u003c\/h2\u003e\n\n  \u003cp\u003eTransform the sound and response of your 3 Series or 4 Series with Stone’s factory-valve-compatible cat back. Developed specifically for the N20 turbo petrol platform, this performance rear section delivers a deeper, sportier note with civilised cruising and real-world refinement. It plugs straight into the original electronic flap system, so the car’s ECU controls the valve as standard. Comfort when you want it, more presence when you press on.\u003c\/p\u003e\n\n  \u003cp\u003eWe have fitted and run this system on our own builds and customer cars. Feedback has been consistently positive - calm on the motorway with minimal cabin boom, crisp and aggressive under load, and excellent fitment thanks to precise engineering. If you are searching for a sports exhaust for F30 320i, F31 Touring 320i, F32 420i coupe, F33 420i cabrio or F36 420i Gran Coupe including xDrive, this is the direct-fit upgrade that keeps OE polish while adding excitement.\u003c\/p\u003e\n\n  \u003ch3\u003eKey reasons to choose this Stone valved system\u003c\/h3\u003e\n  \u003cul\u003e\n    \u003cli\u003eDirect fit for BMW F30 F31 F32 F33 F36 with N20 2.0 turbo 320i and 420i including xDrive\u003c\/li\u003e\n    \u003cli\u003eFactory valve integration - ECU controlled flap operation for seamless drive modes\u003c\/li\u003e\n    \u003cli\u003eRefined tone with minimal drone compared to the stock back box\u003c\/li\u003e\n    \u003cli\u003e3D scanned and reverse engineered for exact OE-style alignment and hanger positions\u003c\/li\u003e\n    \u003cli\u003eDyno developed for improved flow and sharper throttle response\u003c\/li\u003e\n    \u003cli\u003eOne piece construction with precision mechanical welding for durability\u003c\/li\u003e\n    \u003cli\u003eEngineered to cut unwanted cabin resonance while enhancing character\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003ch3\u003eOptional Valvetronic remote control upgrade\u003c\/h3\u003e\n  \u003cp\u003eWant to command the valve yourself at any time? Add the Stone Valvetronic single-valve kit. It includes a plug-and-play OBDII controller and remote, allowing you to open or close the flap on demand. Ideal if you want quiet start early in the morning and a more vocal soundtrack on a spirited drive.\u003c\/p\u003e\n\n  \u003cdiv style=\"margin:14px 0;\"\u003e\n    \u003cstrong\u003eValvetronic control - install overview\u003c\/strong\u003e\n    \u003cdiv style=\"margin-top:8px;\"\u003e\n      \u003ciframe width=\"100%\" height=\"480\" src=\"https:\/\/www.youtube.com\/embed\/V5c4VEyO1EM\" title=\"Stone Valvetronic Install\" frameborder=\"0\" allow=\"accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture\" allowfullscreen=\"\"\u003e\u003c\/iframe\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n  \u003ch3\u003eSound and development\u003c\/h3\u003e\n  \u003cdiv style=\"margin:14px 0;\"\u003e\n    \u003cstrong\u003eBMW N20 F30 320i with Stone OEM downpipe plus Valvetronic cat back - sound clip\u003c\/strong\u003e\n    \u003cdiv style=\"margin-top:8px;\"\u003e\n      \u003ciframe width=\"100%\" height=\"480\" src=\"https:\/\/www.youtube.com\/embed\/BFX0HSexkpI\" title=\"Stone Exhaust BMW N20 320i Sound\" frameborder=\"0\" allow=\"accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture\" allowfullscreen=\"\"\u003e\u003c\/iframe\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv style=\"margin:14px 0;\"\u003e\n    \u003cstrong\u003eBMW N20 F36 420i - full system sound\u003c\/strong\u003e\n    \u003cdiv style=\"margin-top:8px;\"\u003e\n      \u003ciframe width=\"100%\" height=\"480\" src=\"https:\/\/www.youtube.com\/embed\/J_4rDcujVCM\" title=\"Stone Exhaust BMW N20 420i Sound\" frameborder=\"0\" allow=\"accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture\" allowfullscreen=\"\"\u003e\u003c\/iframe\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv style=\"margin:14px 0;\"\u003e\n    \u003cstrong\u003eDyno development\u003c\/strong\u003e\n    \u003cdiv style=\"margin-top:8px;\"\u003e\n      \u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0284\/6300\/5795\/files\/Stone_Exhaust_BMW_N20_B48_F30_F32_Cat-Back_Valvetronic_Exhaust_Inc._320i_420i_600x600.png?v=1590757256\" alt=\"Dyno developed Stone cat back for BMW N20 320i 420i F30 F32\" style=\"max-width:100%; height:auto;\"\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n  \u003ch3\u003eHow Stone achieves OE-level fit and finish\u003c\/h3\u003e\n  \u003cp\u003eStone designs each system using detailed 3D scanning of the original equipment to map pipe diameter, routing and bend angles. Flow, temperature and pressure are simulated to refine performance, then the final product is produced with a 7 axis CNC bending process that keeps up to 98 percent roundness. Critical joints feature overlapping and crisscross welds with mechanical arm spot welding for strength and long service life.\u003c\/p\u003e\n\n  \u003cdiv style=\"margin:14px 0;\"\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=\"3D scanning and R and D for BMW F series sports exhaust\" style=\"max-width:100%; height:auto;\"\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv style=\"margin:14px 0;\"\u003e\n    \u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0284\/6300\/5795\/files\/bending.jpg?v=1572739395\" alt=\"7 axis CNC bending for premium fitment\" style=\"max-width:100%; height:auto;\"\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv style=\"margin:14px 0;\"\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=\"Advanced welding on Stone sports system\" style=\"max-width:100%; height:auto;\"\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv style=\"margin:14px 0;\"\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=\"Precision spot welding for durability\" style=\"max-width:100%; height:auto;\"\u003e\n  \u003c\/div\u003e\n\n  \u003ch3\u003eInstalled photos\u003c\/h3\u003e\n  \u003cdiv style=\"margin:14px 0;\"\u003e\n    \u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0284\/6300\/5795\/files\/Untitled_2e3e0d3f-f88a-4c69-89f1-a48e9b8477e7_600x600.png?v=1588766527\" alt=\"Stone dual exit configuration fitted\" style=\"max-width:100%; height:auto;\"\u003e\n  \u003c\/div\u003e\n  \u003cdiv style=\"margin:14px 0;\"\u003e\n    \u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0284\/6300\/5795\/files\/Untitled1_7e8db30e-c8d4-427a-aaeb-9d917125875a_600x600.png?v=1588766534\" alt=\"Stone cat back fitted on BMW F series\" style=\"max-width:100%; height:auto;\"\u003e\n  \u003c\/div\u003e\n\n  \u003ch3\u003eVehicle compatibility - N20 2.0 turbo\u003c\/h3\u003e\n  \u003cp\u003e3 Series\u003c\/p\u003e\n  \u003cul\u003e\n    \u003cli\u003eF30 320i and 320i xDrive 2011 plus\u003c\/li\u003e\n    \u003cli\u003eF30 LCI 320i and 320i xDrive 2014 plus\u003c\/li\u003e\n    \u003cli\u003eF31 320i 2011 plus and 320i xDrive 2012 plus\u003c\/li\u003e\n    \u003cli\u003eF31 LCI 320i and 320i xDrive 2014 plus\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003cp\u003e4 Series\u003c\/p\u003e\n  \u003cul\u003e\n    \u003cli\u003eF32 420i and 420i xDrive 2013 plus\u003c\/li\u003e\n    \u003cli\u003eF32 LCI 420i and 420i xDrive 2016 plus\u003c\/li\u003e\n    \u003cli\u003eF33 420i 2013 plus and F33 LCI 2016 plus\u003c\/li\u003e\n    \u003cli\u003eF36 420i and 420i xDrive 2013 plus\u003c\/li\u003e\n    \u003cli\u003eF36 LCI 420i and 420i xDrive 2016 plus\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003ch3\u003ePart numbers and outlet styles\u003c\/h3\u003e\n  \u003cul\u003e\n    \u003cli\u003e\n\u003cstrong\u003eAP502\u003c\/strong\u003e - Single left exit with twin tips - uses original bumper\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eAP502N\u003c\/strong\u003e - Dual exit with twin tips - requires 335i or 435i rear bumper\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eAP502NQ\u003c\/strong\u003e - Dual exit with quad tips - requires 335i or 435i rear bumper\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003ch3\u003eInstallation\u003c\/h3\u003e\n  \u003cp\u003eProfessional fitting recommended for best results. Book expert installation with MJ Modifications in Warwickshire. 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\u003eManufactured by\u003c\/h3\u003e\n  \u003cp\u003eStone Exhaust\u003c\/p\u003e\n\n  \u003ch3\u003eSearch terms to help you find this product\u003c\/h3\u003e\n  \u003cp\u003eF30 320i sports exhaust, F31 320i Touring performance system, F32 420i sport exhaust upgrade, F33 420i convertible rear silencer, F36 420i Gran Coupe cat back, N20 turbo sports system, switchable flap exhaust, ECU controlled valve exhaust, OE valve compatible exhaust, BMW 3 Series 320i performance rear section, BMW 4 Series 420i sound upgrade, xDrive compatible cat back, twin tip and quad tip options, dual exit conversion, 335i 435i bumper conversion exhaust, quiet to loud valve exhaust, drone free motorway cruising, direct fit bolt on BMW F series exhaust.\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":56008711242114,"sku":null,"price":2396.16,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0871\/5445\/8937\/files\/BMWN20F30F32_Cat-BackValvetronicExhaust2-2_1024x1024_2x_f56c3841-9d81-4055-9a20-2cb1e0a5a706.webp?v=1764091195","url":"https:\/\/mjmodifications.co.uk\/products\/stone-exhaust-bmw-n20-f30-f32-cat-back-valvetronic-exhaust-inc-320i-420i","provider":"MJ Modifications","version":"1.0","type":"link"}