{"product_id":"stone-exhaust-bmw-n26-f30-f32-cat-back-valvetronic-exhaust-inc-328i-428i","title":"Stone Exhaust BMW 328i\/428i F30 F32 F33 N26 Valved Cat-Back (Catback) Performance Exhaust | Switchable Valvetronic OEM Valve Control | Twin\/Dual\/Quad Tips | Drone-Free Direct-Fit Sports Back Box\/Muffler Upgrade for 3 Series \u0026 4 Series | Rear Section","description":"\u003cdiv class=\"product__description rte\"\u003e\n  \u003ch2\u003eBMW 328i 428i F30 F32 F33 N26 valve-controlled performance exhaust by Stone Exhaust\u003c\/h2\u003e\n\n  \u003cp\u003e\n    Give your turbocharged N26 3 Series or 4 Series the soundtrack and response it deserves. This switchable performance system is a direct replacement for the factory rear section, using the car’s original valve control for quiet cruising and a richer, sportier tone when open. Designed around the OEM layout for factory-style fit and finish, it delivers a deeper note, cleaner flow and crisp throttle response without unwanted cabin resonance.\n  \u003c\/p\u003e\n\n  \u003cp\u003e\n    Prefer manual control on demand? Add the optional Stone Valvetronic single-valve kit with simple OBDII plug-in controller for instant loud or quiet at the touch of a button.\n  \u003c\/p\u003e\n\n  \u003ch3\u003eKey reasons enthusiasts choose this upgrade\u003c\/h3\u003e\n  \u003cul\u003e\n    \u003cli\u003eFactory valve integration for seamless ECU control, smooth in Comfort, full character in Sport\u003c\/li\u003e\n    \u003cli\u003eOptimised flow from Stone’s 3D-scanned, OEM-referenced design for real-world gains on their in-house dyno\u003c\/li\u003e\n    \u003cli\u003eRefined, drone-free cruising with a deeper, more engaging tone under load\u003c\/li\u003e\n    \u003cli\u003eOptional Valvetronic remote valve control via OBDII for plug-and-play switching\u003c\/li\u003e\n    \u003cli\u003eOne-piece layout for strength, leak resistance and consistent performance\u003c\/li\u003e\n    \u003cli\u003ePrecision CNC bending with up to 98 percent roundness to reduce turbulence at tight radii\u003c\/li\u003e\n    \u003cli\u003eRobust mechanical welds with crisscross and overlap techniques for durability at high temperatures\u003c\/li\u003e\n    \u003cli\u003eDirect replacement using factory mounting points for a hassle-free install\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003ch3\u003eCompatible BMW models with the N26 engine\u003c\/h3\u003e\n  \u003cul\u003e\n    \u003cli\u003eBMW 3 Series F30 328i saloon 2011+\u003c\/li\u003e\n    \u003cli\u003eBMW 4 Series F32 428i coupé 2013+\u003c\/li\u003e\n    \u003cli\u003eBMW 4 Series F33 428i convertible 2013+\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003ch3\u003eTip layouts and part numbers\u003c\/h3\u003e\n  \u003cul\u003e\n    \u003cli\u003e\n\u003cstrong\u003eAP501N26\u003c\/strong\u003e  Left single exit with twin tailpipes\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eAP512N26\u003c\/strong\u003e  Dual exit with one tailpipe each side\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eAP512QN26\u003c\/strong\u003e  Dual exit with quad tailpipes\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003ch3\u003eEngineering detail that makes the difference\u003c\/h3\u003e\n  \u003cp\u003e\n    Stone engineers 3D-scan the factory exhaust to map diameters, routing and bend angles, then iterate with flow, thermal and pressure simulations to refine the design. A 7-axis CNC bending process maintains exceptional roundness through bends for stable gas speed and reduced turbulence. Crisscross and overlapping welds increase penetration and width, while precision spot welding by mechanical arms ensures consistent strength and a clean finish.\n  \u003c\/p\u003e\n\n  \u003ch3\u003eWhat drivers say\u003c\/h3\u003e\n  \u003cp\u003e\n    We have fitted this system to our own cars and for many customers, and the feedback is consistently positive. Fitment is spot on, the cruising refinement is excellent, and when the valve opens the car gains a properly sporty tone without cabin boom. It is a brilliant upgrade for daily use that still brings the weekend excitement.\n  \u003c\/p\u003e\n\n  \u003ch3\u003eFitting and support\u003c\/h3\u003e\n  \u003cp\u003e\n    Professional installation available at MJ Modifications in Warwickshire. For a fitting quote or advice email \u003ca href=\"mailto:info@mjmodifications.co.uk\"\u003einfo@mjmodifications.co.uk\u003c\/a\u003e.\n  \u003c\/p\u003e\n\n  \u003ch3\u003eWarranty and manufacturer\u003c\/h3\u003e\n  \u003cp\u003e\n    Stone Exhaust 2 year warranty. Manufactured by Stone Exhaust.\n  \u003c\/p\u003e\n\n  \u003ch3\u003ePopular searches\u003c\/h3\u003e\n  \u003cp\u003e\n    BMW 328i performance exhaust F30, BMW 428i sports exhaust F32, BMW 428i convertible exhaust F33, switchable exhaust 328i, valve controlled exhaust 428i, ECU flap exhaust upgrade N26, BMW 3 Series rear silencer upgrade, BMW 4 Series quad tip exhaust, twin tip exhaust 328i, dual exit exhaust 428i, plug and play OBD2 valve controller, no drone BMW exhaust, UK BMW exhaust specialist, direct fit exhaust for F30 F32 F33, back box upgrade 328i, performance system for N26 turbo petrol.\n  \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":56008723726722,"sku":null,"price":2396.16,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0871\/5445\/8937\/files\/BMWN26F30F32_Cat-BackValvetronicExhaust3-2_1024x1024_2x_0e047a24-7518-4337-873d-a9ad250fe4e6.webp?v=1764091369","url":"https:\/\/mjmodifications.co.uk\/products\/stone-exhaust-bmw-n26-f30-f32-cat-back-valvetronic-exhaust-inc-328i-428i","provider":"MJ Modifications","version":"1.0","type":"link"}