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BMW 118i Performance Tuning Guide

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Table of Contents


Although producing respectable power in its own right, the true essence of the BMW 118i is unveiled when you start exploring the tuning possibilities.

The car’s turbocharged nature allows for impressive power gains via tuning, with plenty of safe and proven ways to boost your 118i’s power output.

Let’s take a look at the most effective and safe ways to tune your 118i and gain some extra performance.

For this guide we will primarily be focusing on the second and third generation of the 118i (F20/F21, F40).

Performance Exhaust

Upgrading to a free flowing aftermarket exhaust system will improve your 118i’s performance as well as produce a nice deep exhaust note. 

By reducing the restrictions in the exhaust system, an aftermarket exhaust can expel the exhaust gasses more efficiently and reduce backpressure. This results in increased horsepower, torque and a more responsive throttle. 

If you are after maximum performance, then you will want to start by replacing the downpipe and catalytic converter section of the exhaust. This section of the exhaust is nearest the turbo and is responsible for most of the restriction and backpressure. 

The downpipe leads into the catalytic converter section of the exhaust.

You have 2 options at this point.

You can replace the standard catalytic converter with a decat pipe which essentially just bypasses it with a straight pipe. While increasing performance and sound, this isn’t road legal.

The other more popular option is to replace the standard catalytic converter with a “sports cat”. This is a more free flowing catalytic converter aimed at increasing performance while remaining compliant for emissions tests and regulations. 

After this you have the cat-back section. 

This is made up of your muffler/backbox and is responsible for controlling the sound and toning it down. Opting for a free flowing cat-back which improve performance as well as obviously produce a nice sporty exhaust note. 

For maximum performance gains, replacing the downpipe, catalytic converter and backbox with a free flowing option will produce the best results. 

If you are just after increased sound, then an aftermarket cat-back will be sufficient. 

Aftermarket Air Filter

With an aftermarket air intake, you can help boost the air flow going into the engine as well as increase the induction sounds. 

For the 118i, you have the option of upgrading to an aftermarket panel filter from a manufacturer like Pipercross or upgrading to an aftermarket induction kit that replaces the factory airbox.

Which option you decide to go for will depend on your budget and goals. 

The cheaper of the two is going to be the panel filter. An upgraded panel filter allows for increased air flow over the standard filter, which can marginally improve power gains. They are also more durable and last longer than the standard paper filters. 

If you are after maximum performance and sound gains, then an induction kit is your best bet. 

The MST intake is a solid option with proven dyno gains. 

This induction kit comes with a heat shield to ensure the intake is sucking in as much cool air as possible along with a silicone inlet elbow.

Installing a cold air intake doesn’t just improve your BMW’s performance but also delivers a deeper, more aggressive induction sound. So if you’re after increased sound, definitely go for the cold air intake over the upgraded panel filter. 

118i MST Intake

MST Intake

For the 118i

Pipercross Panel Filter

For the 118i

Upgraded Intercooler

An aftermarket intercooler plays a vital role in enhancing your 118i’s performance by efficiently cooling the charge air. As a result, this allows for a significant increase in the density of air entering the combustion chamber, leading to increased power.

One of the biggest advantages of an aftermarket intercooler is the larger core which is responsible for the performance improvements.

This features a larger surface area, letting the charge air pass through more cooling tubes and fins, facilitating a more efficient heat exchange. Due to it’s larger size, these intercoolers are less susceptible to heat soak, a condition that occurs when the intercooler can’t keep up with the heat being produced by the engine and loses its cooling efficiency.

The benefits become most prominent after periods of hard driving where the turbo get’s hot. You may notice this after long hard driving sessions where you are on boost a lot and feel a loss in power after a short while. An aftermarket intercooler aims to prevent this. 

Wagner offer a solid intercooler kit that has a 64% larger frontal area for maximum cooling capacity during hard driving. This doesn’t require extensive modification of your 118i to fit such as cutting into the bumper or needing custom pipework. 

You also have the option of the Masata Intercooler which is a quality alternative and claims to make power gains of 10whp!

Paired with other mods and a remap these can make a noticeable performance difference if you like to drive hard.


A remap is one of the most effective value for money mods you can do if you are after a power upgrade. Even without other physical mods fitted to the car, you will still notice a difference in power. 

It’s not just about the power that a remap adds tot he car, but how much the overall drivability is improved. A bespoke remap will give you more horsepower and torque throughout the rev range, making power much more accessible for daily driving. 

It’s a good idea to check over your car and give it a proper health check before having it tuned. Many tuning workshops will do this for you prior to remapping it. Coil packs and spark plugs are components that are often recommended to be looked at and changed if you’re looking to tune these cars. 

The power gains you get will depend on the health of your engine/turbo and what model of the 118i you own.

For example on the 167bhp models, you can achieve a +35bhp increase and +40 lb-ft increase in torque.

On the 134bhp model, power gains of +40bhp are achievable along with +40 lb-ft of torque.

This is with just a remap!

Power gains will be higher if you have other performance mods fitted to the car prior to remapping.

Lowering Springs

Lowering springs are a simple and cost effective mod that improves the look and handing performance of your 118i.

Many owners install them for the aesthetic benefits, however they also offer improved performance.

Lowering the ride height of your BMW will lower it’s centre of gravity, which in turn can improve overall handling and stability. Ideal for taking those corners!

In terms of a visual upgrade, lowering springs reduce the wheel arch gap, giving it a more sporty stance and streamlined look.

Before investing in lowering springs, be mindful of what model of the 118i you have. The M Sport version of the 118i has a slightly lower suspension than the non M Sport models. 

Some lowering spring manufacturers will quote the drop height based on the standard model, so if you have an M Sport 118i then subtract 15mm from the quoted drop.

There are different options available, with reputable manufacturers like Eibach and H&R offering quality lowering springs. 

The most common drop height is between 25mm – 35mm. 

118i Lowering Springs

Eibach 30mm Lowering Springs

For the 118i

Finishing Thoughts

We hope you found this guide useful at giving you some ideas on how to boost the performance of your 118i.

For increasing power, a full upgraded exhaust, upgraded intercooler and an intake along with a remap will get you the majority of gains on these engines without further drastic work like an uprated turbo. 

Remember to have your physical mods fitted prior to remapping for the best results. 

For some additional aesthetics and stiffer handling, a set of lowering springs are a good option. If you want to increase your handling further, you can also look into coilovers or stiffer anti-roll bars however you may start compromising the ride comfort when you go with some of these handling mods. 

Happy modding!