MST Performance BMW X3/X4 M40i Air Intake Kit

MST Performance BMW X3/X4 M40i Air Intake Kit (MST-BW-X301)

If you want more from your BMW X3 or X4 M40i, improving the way the engine breathes is one of the most straightforward upgrades you can make. This air intake kit from MST Performance replaces the standard airbox with a freer-flowing setup, giving the engine better access to cold, fresh air and helping it perform closer to its full potential.

The kit is designed for the 2017-2020 BMW X3 and X4 fitted with the 3.0-litre turbocharged B58 petrol engine – the same unit found in the M40i variants. Use the vehicle lookup tool on this site, or check the Vehicle Fitment tab, to confirm compatibility with your specific model before ordering.

What It Does and Why It Matters

The factory airbox on these BMWs is designed with packaging and noise regulations in mind, not outright performance. It can restrict airflow to the turbocharger (the forced-induction unit that pressurises air into the engine). By replacing it with MST’s larger-diameter inlet pipe and open filter, more air reaches the turbo more efficiently. The result is improved throttle response – meaning the car feels more immediate and eager when you press the accelerator – along with a more noticeable induction sound under load.

MST quote maximum power gains of 12-14bhp on the dyno (a controlled test that measures engine output). Real-world figures will vary depending on the condition of your vehicle and whether it has been tuned, but this is a realistic and well-supported improvement for a bolt-on modification. On an already tuned B58, the kit helps ensure the engine can make the most of any additional fuelling or boost adjustments already in place.

What’s Included

• Black powder-coated heat shield – helps isolate the filter from engine bay heat, keeping intake temperatures lower
• Black powder-coated aluminium inlet pipe
• Red dry pleated performance air filter – easy to clean and reuse, no oiling required
• Silicone joiner – connects the pipe to the turbo inlet
• Full fitting hardware and step-by-step instructions

Installation and Maintenance

The kit is designed to fit using standard hand tools and comes with clear fitting instructions, making it suitable for a competent home mechanic. If you are not confident working on your vehicle, fitting by a qualified technician is always recommended. The dry pleated filter can be cleaned and reused, keeping long-term maintenance simple and cost-effective.

For full vehicle compatibility details, please use the site’s vehicle lookup tool or refer to the Vehicle Fitment tab on this page.