Stay in the loop with the latest updates, offers, and more—sign up now and start saving!
When BMW introduced the G20 M340i, it effectively bridged the gap between the standard 3 Series and the full-fat M3. With its B58TU engine, xDrive capability, and modern chassis dynamics, it offers immense tuning potential—especially when approached with mechanical sympathy and well-matched upgrades.
This particular white G20 M340i arrived at Xatrix for its first round of upgrades aimed at unlocking a stronger base setup: better breathing, improved boost control, and stronger fueling. The goal? A fast, road-capable car that feels OEM+ but delivers noticeably more punch.
A few months later, the car returned for Phase 2—a more aggressive overhaul designed to chase the 600bhp mark while maintaining daily usability. From turbo upgrades to flash tuning and suspension, this stage dialled in both power and control.
The focus of the first stage was to improve the engine’s efficiency under increased demand. We wanted the car to breathe better, run cooler under pressure, and prepare safely for future power gains—without flashing the DME just yet.
The Burger Motorsports Intake was the first step in improving breathing efficiency. Featuring a free-flowing cone filter and smooth piping geometry, it allows the turbo to draw in cooler, denser air with less restriction than the stock airbox. This alone sharpens throttle response and sets the tone for a more responsive turbo setup.
Crucial for intake charge cooling and detonation resistance, the WMI kit was installed to help manage higher boost levels safely. Under load, the meth mix significantly reduces intake temps and increases effective octane—essential for high-power B58 builds running on UK pump fuel. It’s not just about numbers; it’s about reliable, repeatable performance.
The JB4 from BMS acts as a gateway mod for the M340i. Offering on-the-fly map switching, CANbus integration, and user tunability, it allows for moderate boost increases, fuelling tweaks, and basic datalogging—all without touching the factory ECU. Paired with WMI, it’s a powerful interim solution before moving to full flash tuning.
The STROM alloys improve unsprung weight and bring a sharper, more aggressive stance without compromising ride quality. Fitment is tailored to the M340i’s wide arches, offering better grip and visual presence.
Subtle additions like a front splitter, side skirt extensions, rear diffuser, and a boot-mounted wing enhance both aesthetics and airflow management. While mostly visual, they add a motorsport-inspired presence and support the OEM+ theme of the build.
Several months after Phase 1, the customer returned to Xatrix ready to step things up significantly. Phase 2 focused on serious hardware and software changes—enabling more power, better tuning control, and upgraded chassis dynamics to keep it all in check.
Adjustable in both height and damping, the ST XA coilovers give this M340i the ability to dial in ride quality and cornering response. Body roll is reduced, feedback is sharper, and the car remains compliant enough for daily use—ideal for a street build targeting big numbers.
To move beyond the limitations of JB4, we performed a FEMTO unlock on the factory DME, enabling full flash tuning capabilities via MHD. This allows for advanced boost control, ignition timing, fuelling calibration, and datalogging—all essential for extracting the most from the upgraded turbo while maintaining safety.
The crown jewel of Phase 2, the Vargas GCB58TU hybrid turbo is designed to deliver serious top-end power without sacrificing spool characteristics. Built with upgraded internals, enlarged compressor/turbine wheels, and reinforced housings, this turbo is rated for well over 600bhp and pairs perfectly with methanol injection and custom mapping.
Since installing the Endless ME22 Front Brake Pads, the braking performance has been transformed. The sharp initial bite and fade-free stopping power make a huge difference, especially during aggressive driving or track sessions. Pedal feel is consistent and confidence-inspiring, allowing for precise control under pressure. If you want to brake harder, later, and with total confidence — these pads are a game-changer.
This G20 M340i is a textbook example of how a modern performance car should be upgraded: in stages, with purpose, and with long-term goals in mind. Each phase had a clear intent—Phase 1 focused on prepping the car to handle more power safely, and Phase 2 delivered the serious gains in output and handling finesse.
By separating the work into two visits, the customer not only got to enjoy the benefits of each stage but also allowed the car to evolve intelligently. From hardware to tuning strategy, every part was selected with both performance and reliability in mind.
This isn’t just a fast M340i—it’s a balanced, OEM+ street build with genuine performance pedigree.
If you’ve put together something special using parts from ML Performance, get in touch! Whether it’s a street build, a track monster, or an OEM+ daily driver—we’d love to showcase your journey.
📧 info@mlperformance.co.uk
📲 DM us on Instagram: @mlperformanceuk
