The MAD BMW M340 M440 Axle Back Exhaust System is designed to deliver a bold sound upgrade without unnecessary parts or added cost. On this platform, a full catback is simply not needed. The factory midpipe is already a single design and is completely non-restrictive, with no cats and no resonators. Replacing it with another single midpipe offers no real performance or sound benefit, so this system focuses where it actually matters: the axle back.
ETA: May 2026
This axle back setup dramatically improves sound and character while keeping the factory midpipe in place, making it a smarter and more efficient upgrade. It gives the car a deeper, more aggressive tone when pushed, while staying refined and comfortable during normal driving.
The system includes three tip options. Available finishes are brushed stainless, black, or carbon, allowing you to tailor the look to your build.
Installation is quick and straightforward. As with most axle back systems, cutting the factory pipe is required. The process is very simple, takes minimal time, and the provided clamps make installation clean and secure.
The exhaust is constructed from high-quality 304L stainless steel for excellent durability and long-term corrosion resistance.
An upgraded dual valve configuration converts the factory single valve setup into a true dual valve system similar to M models. The factory valve actuator is reused, with an additional valve added on the opposite side. This allows the exhaust to function perfectly with OEM drive modes, staying quiet in Comfort and opening up fully in Sport.
This axle back is ideal for drivers who want a noticeable sound upgrade, strong presence, and clean fitment without paying for parts that do not add value.
Features:
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Slip on axle back design for BMW M340i and M440i.
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Dramatic sound improvement while keeping factory midpipe in place.
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Included extra Valve motor and harness for a true dual M-style exhaust valve control.
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Retains OEM drive modes: quiet in Comfort, fully open in Sport.
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Three tip options: brushed stainless, black, or carbon.
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Constructed from premium 304L stainless steel for corrosion resistance and longevity.
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Quick and straightforward installation with included clamps.
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No unnecessary components, making it a cost-effective, value-focused upgrade.
Fitment includes
BMW M340i and M440i 2018 and up including G20 and G22
BMW M340i and M440i 2025 and newer models
Compatible with rear wheel drive and xDrive models