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Stone Exhaust

Stone Exhaust BMW N20 F25 X3 28i & F26 X4 28i xDrive Valvetronic Cat-Back Exhaust System (2013+) – Valved, No-Drone, Plug & Play OBDII Controller

Stone Exhaust BMW N20 F25 X3 28i & F26 X4 28i xDrive Valvetronic Cat-Back Exhaust System (2013+) – Valved, No-Drone, Plug & Play OBDII Controller

£2,710.08
£3,387.60 £2,710.08
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Heads-up on cancellations & returns: if you cancel an order or return an item, you won't get back 100% of what you paid. We apply a 10% restocking fee, the outbound shipping is non-refundable, and we have to pass on Shopify / PayPal payment processing fees; these aren't returned to us when we refund you. International orders also lose on exchange-rate spread in both directions. If the original packaging is damaged or missing, a reboxing charge applies. For international orders specifically, if you refuse to pay our shipping invoice or supply a prepaid label after placing the order, the same deductions apply. We're upfront about this — please be sure of your purchase before ordering.

Switchable Catback for BMW F25 X3 28i and BMW F26 X4 28i xDrive 2013 onwards

Give your 2.0 turbo BMW the soundtrack and response it deserves with the Stone valve controlled catback system for the F25 X3 28i and F26 X4 28i xDrive. This premium rear section upgrade is designed around the N20 engine and delivers a deeper, richer tone in Sport while remaining neighbour friendly in Comfort. Expect sharper throttle feel, tasteful cabin character and OEM quality fitment with a simple plug in control module via the OBD port.

We have installed and driven this system extensively at MJ Modifications. Feedback from owners is consistently positive on the sound quality, drone free cruising and the slick factory style fit. If you are searching for a BMW X3 28i sports exhaust, BMW X4 28i xDrive switchable exhaust, N20 2.0T catback or a remote valve exhaust for F25 or F26, this is the one to choose.

Key reasons enthusiasts choose this system

  • Switchable valve control with quiet, aggressive and automatic rpm based modes
  • Plug in OBD controller and remote for fast, tidy installation and easy operation
  • Drone free refinement at motorway speeds with a deep, classy tone under load
  • One piece layout for consistent flow and durability
  • 7 axis CNC bent pipework and precise welds for strength and repeatable alignment
  • Developed using 3D scanning, reverse engineering and in house dyno validation
  • Direct replacement using factory mounting points for genuine OEM like fit

How the valve control works

The included controller plugs into your OBD port. Use the remote to choose:

  • On mode for maximum sound and flow
  • Off mode for refined, neighbour considerate cruising
  • Auto mode to open at your chosen rpm threshold

No cutting of wiring is required. It is a clean, reversible install that retains full control in the cabin.

Compatibility

  • BMW F25 X3 28i including xDrive
  • BMW F26 X4 28i xDrive
  • Model years 2013 onwards where applicable

Exit styles and part numbers

  • AP541BS - Single left exit with twin tips, suits the original bumper
  • AP536BS - Dual exit with twin tips, requires M40i bumper
  • AP536BSQ - Dual exit with quad tips, requires M Sport bumper

Please select the configuration that matches your rear bumper style. Tip layout and bumper cut outs must correspond.

Engineering detail that makes the difference

Stone maps the factory system with high resolution 3D scanning, then optimises gas flow, bend angles and routing for the N20 platform. The result is a performance catback that enhances tone and response without compromising everyday comfort.

Manufacturing highlights include 7 axis CNC bending for exceptional roundness, crisscross and overlapping welds in high temperature zones and consistent spot welding by mechanical arms for strong, repeatable joints. It looks as good as it sounds.

Hear it

Stone valve control module overview

BMW F26 X4 28i xDrive with Stone switchable catback

Images

Stone Exhaust BMW F25 F26 N20 catback valve controlled system 1
BMW X3 X4 28i switchable exhaust rear section 2
Performance catback for BMW N20 F25 F26 3
BMW F25 F26 valve control exhaust components 4
Stone Exhaust catback kit tip options 5
BMW X3 X4 28i twin and quad exit configuration 6

R and D and simulation

Using 3D modelling and simulation, the team analyses pipe diameter, bend radii and heat zones, then iterates to maximise gas velocity and maintain cabin refinement. The end product is a direct fit catback that elevates your BMW X3 28i or X4 28i xDrive without compromise.

3D scanning and reverse engineering for BMW N20 exhaust development

Manufacturing focus

7 axis CNC bending preserves internal diameter and flow. Overlapping and crisscross welds add strength where heat is highest. Robotic spot welding ensures consistent penetration and a long lasting joint. It is engineered for daily use and weekend fun.

Precision welding on performance exhaust systems 1
Precision welding on performance exhaust systems 2

Warranty

Backed by a 2 year warranty from Stone.

Professional fitting by MJ Modifications

Want it installed perfectly first time. Book expert fitting with MJ Modifications in Warwickshire. Request a quote at info@mjmodifications.co.uk.

Searching for the right upgrade

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