The BMW M140i is a powerhouse in the hot hatch world, combining the practicality of a hatchback with the thrill of a rear-wheel-drive sports car. It’s the last of a dying breed, with a 3.0-litre turbocharged inline-six engine that delivers impressive performance straight from the factory. But as any enthusiast knows, there’s always room to push the boundaries. This article will guide you through the best modifications to take your M140i to the next level.
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1. ECU Remapping
The twin-scroll turbocharger and direct fuel injection system of the MW140i’s B58 engine is known for its performance and power delivery, but like many factory-tuned cars, it’s held back by conservative settings designed to meet emissions and reliability standards across global markets. This is where ECU remapping comes into play, offering one of the most significant and cost-effective performance upgrades available.
What is ECU Remapping?
ECU remapping involves altering the software within your car’s Engine Control Unit (ECU) to optimise parameters like fuel delivery, turbo boost pressure, and ignition timing. The result? More power, better throttle response, and improved torque—all tailored to your specific driving style and needs.
For example, a Stage 1 remap on the M140i typically increases horsepower from the stock 335hp to around 400hp, with torque climbing from 369lb/ft to approximately 450lb/ft. And this is without any additional modifications. If you’re willing to go further, a Stage 2 remap, combined with supporting mods like an upgraded intercooler and high-flow downpipe, can push these numbers even higher.
Choosing the Right Tuner
The key to unlocking maximum gains from an ECU remap is using a reliable and knowledgeable specialist. Tuners like Bootmod3 and MHD are highly respected in the BMW community, offering extensive customisation options and proven results. They provide you with the ability to adjust your car’s performance on the fly, perfect for those who like to tinker with their setup.
2. Exhaust System
As stock exhausts go, the M140i sounds great straight from the warehouse. However, if you’re looking for an increase in performance or a more aggressive sound, an aftermarket exhaust system is a great choice. An upgraded exhaust system will reduce back pressure and allow the engine to breathe more freely, resulting in better efficiency and, most importantly, improved power.
You can expect a modest increase in horsepower—typically around 10-15hp—with a well-designed exhaust system. More importantly, you’ll notice improved throttle response and a more defined sound. Brands like Remus and Akrapovič offer systems specifically designed for the M140i, balancing performance gains with an enhanced exhaust note.
When considering an exhaust system, it’s important to think about what you want to achieve. If you’re after a deeper, more resonant sound, a cat-back system might be ideal. On the other hand, if maximum performance is your goal, a turbo-back system with a high-flow downpipe will be more effective, though it may be louder and impact emissions compliance.
3. Cold Air Intake
Life most cars straight from the manufacturer, the stock air intake on the M140i was designed to balance cost-efficiency, sound and airflow. As a result, there’s definitely room for improvement, especially if you’ve had or are considering a remap. An aftermarket cold air intake can enhance engine sound, improve throttle response, and contribute to better power delivery, but it’s important to understand what type of intake is going to provide the result you’re looking for.
Possibly the most noticeable benefit of an aftermarket air intake is the improved induction sound, which adds a more aggressive note to the engine. Power gains will be modest, typically around 5 to 10hp, but when combined with an ECU remap along with other improvements, your car will be noticeably more powerful.
One of the most popular intakes for the M140i F20 and F21 comes from MST Performance. MST claim dyno results ranging from 12-14bhp, and at £399, it’s one of the most competitively priced kits on the market. If you’re looking for something a little more special, Eventuri offers a Carbon Performance Intake for the B58. The carbon fibre and aluminium system improves airflow and keeps intake temperatures low. The kit includes a high-flow air filter, carbon fibre components, heat shields, and precise fittings, all aimed at boosting your engine’s performance. It’s a well-engineered system that’s worth considering if you want to get the most out of your B58 engine.
Eventuri BMW B58 Carbon Performance Intake System
MST Performance BMW M140i F20 & F21 Intake Kit
4. Coilovers and Lowering Springs
Upgrading the suspension on your BMW M140i is a smart move to improve both the car’s appearance and handling. Lowering your car not only gives it a more aggressive stance but also enhances its performance on the road. Here’s a straightforward guide to your options: coilovers and lowering springs.
Coilovers
Coilovers are the top choice if you want the best control over your M140i’s handling. They combine the spring and shock absorber into one unit, making installation simpler and improving performance. With coilovers, you can adjust both the ride height and the firmness of the suspension independently, allowing for a custom setup tailored to your driving style, whether it’s daily driving or track use.
Coilovers can significantly improve your car’s cornering ability, reduce body roll, and overall make the car more enjoyable to drive. Brands like KW, Bilstein, and H&R offer high-quality coilovers designed specifically for the M140i, ensuring a perfect fit and durable performance. Prices typically range from £1000 to over £4500, depending on the brand and features.
Lowering Springs
If you’re looking for a more budget-friendly option, lowering springs are a great alternative. They lower your car and stiffen the suspension, which reduces body roll in corners and improves handling.
While lowering springs don’t offer the adjustability of coilovers, they still make a noticeable difference in your car’s performance. They’re easier to install and less expensive, making them a popular choice for people new to card modifications.
Eibach M140i Motech Stance+ Lowering Springs
Lowers Front 30mm and Rear 25mm
H&R BMW M135i F20/F21 Lowering Springs
Lowers Front and Rear 25mm
Important!
Whether you choose coilovers or springs, lowering your car will change its alignment and potentially affect tyre wear and handling. We recommend getting your car checked and realigned after you make any changes to your suspension.
5. Alloys
Upgrading the wheels on your BMW M140i is one of the most popular and impactful modifications you can make. While some of the stock alloy options, like the 18″ M Double-Spoke wheels, are already quite attractive, there are plenty of aftermarket options that can take your M140i’s look to the next level.
If you’re aiming for an OEM+ upgrade, the 19″ M Performance Double-Spoke wheels are a fantastic choice. They offer a sportier, more aggressive appearance while maintaining the refined look that BMW is known for. However, keep in mind that upgrading to 19″ wheels can make the ride a bit harsher, particularly on rough roads. Despite that, the enhanced aesthetics and improved handling are often worth the trade-off.
Top OEM+ Choices:
- BMW M Performance Double-Spoke 19″: The BMW 405M Sport Y Spoke 19″ wheels are a standout option. These wheels are part of BMW’s M Performance lineup, known for their striking design and high-quality construction, making them a popular OEM+ upgrade.
- BMW 704M 18″: Another great OEM option, these wheels offer a sporty look with a slightly more forgiving ride than the 19″ options.
BMW 405M Sport Y Spoke 19 OEM+
BMW 704M 18′ OEM
Aftermarket Options
Apex EC-7:
Apex EC-7 wheels are well-regarded in the BMW community for their track-oriented design, strength, and lightweight construction. These wheels offer excellent brake clearance and are available in various sizes and offsets, making them a perfect fit for the M140i.
HRE FlowForm FF01:
HRE is known for producing high-quality wheels, and the FlowForm FF01 combines premium style with performance. These flow-formed wheels are lighter and stronger than typical cast wheels, and they come in fitments that suit the M140i perfectly.
VMR V710:
VMR V710 wheels offer a classic mesh design that gives the M140i a sporty and aggressive stance. They are a more budget-friendly option that doesn’t compromise on style or quality, with fitments that work well for the M140i.
Apex EC-7
HRE FlowForm FF01
VMR V710
To wrap things up, upgrading your BMW M140i with the right mods can really elevate its performance and driving experience. Whether you’re looking for more power, better handling, or a fresh look, these modifications are a great way to make your car truly yours. Just make sure to choose quality parts and have them installed by a professional to get the best results. Enjoy the ride!
