The 5 Best Mini Cooper S Performance Upgrades

The third generation Mini Cooper S received a larger 2.0L turbocharged I4. The engine is BMW’s B48 engine, which produces 189hp and 207lb-ft. of torque. In 2020 Mini launched a John Cooper Works GP, a track-focused version of the Cooper S. The JCW GP also uses the 2.0L B48, but produces 302hp and 332lb-ft. of torque.

For around $1,500 you can purchase a tune, intake, downpipe, and intercooler all of which, along with E85 fueling, will add more than 100whp to the Mini Cooper S. Ultimately, creating a 300whp car that is lightweight and super fun. We’re going to discuss each of these performance upgrades below including their power gains, benefits, and more. Lastly, we’ll discuss the max power limits of the B48 engines they use.

Best Mini Cooper S Performance Upgrades

• ECU Tuning
• High Flow Downpipe
• Cold Air Intake
• Intercooler
• Fueling (E85)

If you would rather consume this content via a video, check out our How to Build a 300 WHP Mini Cooper S with only $1,500 video below:

1) ECU Tuning

The hands down best performance modification for the Mini Cooper S is a tune. A simple plug-and-play tune can add 40whp with zero additional modifications. Additionally, it will amplify the power gains from subsequent modifications so it is one of the best building blocks for performance upgrades. The two popular tuning options for the B48 in the Cooper S is the JB4 piggyback tuner, and the MaxxBoost flash tuner.

The main difference between the two is how they go about tuning the car. The JB4 is a piggyback tuner which means it doesn’t actually alter the factory ECU settings, and therefore is undetectable by a dealership if the tune is removed. The MaxxBoost tuner actually reflashes the ECU, changing the cars factory parameters. Piggyback tunes are the easiest to setup and use and come with multiple different maps or tunes. The MaxxBoost tune can handle custom tunes but doesn’t come with as many pre-programmed options.

Mini Cooper S Tune Power Gains

• Up to 40whp and 40wtq power gains
• Simple plug-and-play setup
• Increases power gains from subsequent mods
• Best price per hp upgrade

2) High-Flow Downpipe

The second best bang-for-the-buck mod for the Cooper S B48 is an upgraded downpipe. A freer flowing (catless) downpipe will provide 10-15whp and 15-20wtq, the second best gains of any mod behind a tune. However, one of the biggest benefits is turbo spool. Since the downpipe houses the catalytic converter it creates a lot of exhaust backpressure. Since the downpipe bolts directly to the turbo, the backpressure negatively impacts turbo spool. It acts as a negative force against the turbine wheel, preventing its ability to spool and build boost quickly.

You want the biggest pre-turbo to post-turbo pressure drop and the easiest way to achieve this is with a catless downpipe. However, catless downpipes are technically illegal. Therefore, the alternative option is to opt for a high-flow downpipe. Gains from a high-flow downpipe will probably be about 5whp less than a catless option. But it keeps your Mini emissions legal (in most states).

Downpipe Upgrade Benefits

• 10-15whp and 15-20wtq gains (about 5 less for high-flow)
• Big benefit to low-end torque
• Faster turbo spool and better throttle response
• Significant exhaust backpressure reduction (less stress on turbo)
• Slightly louder exhaust note

3) Cold Air Intake

Our third favorite performance upgrade for the Cooper S is an upgraded intake. Tunes primarily create more powering by increasing the amount of boost the turbo is creating. The more boost you are pushing the more air you need to be bringing into the engine. The stock intake on the B48 is actually pretty good, but it can become slightly restrictive if you are pushing high boost levels.

An upgraded intake will provide about 5whp and 5wtq gains. While these numbers aren’t super impressive, bringing more air into the engine helps improve the efficiency of the turbo and reduce the amount of stress being put on it. You can run a tune on the stock intake, but at $199 it doesn’t make sense to put the extra stress on your turbo.

We recommend using an open intake system, where the air filter is directly exposed to the engine bay. The alternative is using a closed system where the filter sits within an enclosed box, similar to the stock intake. Since the stock intake is pretty good, you aren’t really going to see any gains unless you use an open intake. The goal is to maximize airflow and an open intake will provide the best airflow gains over the factory air box.

Upgraded Intake Benefits

• 5whp and 5wtq power gains
• Better throttle response
• Faster turbo spool
• Increased turbo efficiency
• Cool intake ‘whoosh’ noises

4) Intercooler Upgrade

Unlike the air-to-water intercoolers used in B48 BMW’s, the B48 in the Mini Cooper S uses an air-to-air intercooler. And since the Mini is a small car, the intercooler is rather small as well. When you’ve added a tune, intake, and downpipe to the S, you’re going to be pushing nearly 60whp more than stock. Ultimately, you’re going to be pushing a lot more air into the engine and therefore through the intercooler.

The small size of the stock intercooler means it can become easily overwhelmed, causing heat soak. Heat soak occurs when the intercooler can’t adequately cool the charge air and essentially passes hot air into the engine bay. Heat soak can cause power losses of 20-30whp when driving aggressively, such as on the track. Upgrading the intercooler is comprised of increasing both the surface area and the core.

A larger intercooler core means it can hold more charge air. And a larger surface area provides better cooling capacity and efficiency. An intercooler such as Wagner’s Competition intercooler provide a 53% larger surface area and 52% larger core size. Not only does this provide solid power gains, it also prevents power loss during hard driving. Additionally, since heat is bad for engines, an intercooler is also one of the best reliability mods for tuned and modified Mini Cooper S’s.

Cooper S Performance Intercooler Benefits

• Approx. 10whp and similar torque gains
• Prevents heat soak and power loss
• Provides more consistent performance
• Lower IATs and EGTs is beneficial for reliability

5) Fueling: E85 Mixtures

With a tune, the B48 can safely run 20%-30% E85 mixtures. E85 burns cooler than traditional gas and has a higher octane. This not only reduces chances of knock or pre-detonation, but also creates more power by allowing for more boost and ignition timing.

The biggest gains will be seen from running 100% E85. However, doing so will require a number of fueling upgrades and custom tuning. Therefore, the simplest way to get gains out of E85 is by running a 20%-30% mix. Running full E85 is a great option once you start looking into turbo upgrades and maximizing power potential.

Mini E85 Fueling Benefits

• 10whp-30whp+ gains and similar torque gains
• Decreased chance of knock and pre-detonation
• Allows for more boost
• Can run more aggressive ignition timing

Running 20%-30% E85 mixtures will yield power gains on the lower end of the range. To see 30whp+ gains you are going to need to run 100% E85. At a minimum running fuell E85 will require an upgraded LPFP and a custom tune. Depending on your setup, you might need port injection.

2.0L Mini Cooper S Power Limits

The stock turbo and fueling limits can get the Mini Cooper S to about 300whp. You can hit these power levels with all of the mods we discussed on this list, which should only cost a few thousand dollars. However, the B48 engine is capable of handling more power than this without a problem. Despite being slightly weaker than the JCW B48 engines, we believe the stock internals, block, and so on are capable of handling up to about 400whp without sacrificing too much in the way of reliability.

The JCW GP engines are a bit different and more power capable than the Cooper S B48’s. The JCW GP engines have a stronger crank, pistons, and bearings and also run a lower compression ratio. So they are stronger than the Cooper S engine and won’t run into internal issues until beyond the 400whp mark.

300whp For Just $1,500

While the Mini Cooper S with the 2.0T B48 only makes 189hp from the factory, it is capable of producing a lot more power. Just five simple bolt-on modifications can easily add nearly 100whp to the Cooper S and get it right around the 300whp range. The best mod, if you are only going to do one, is a tune as it provides the biggest power gains at the most affordable cost. With a tune installed we recommend an intake and downpipe upgrade to help improve airflow and reduce backpressure, creating a more efficient and faster spooling turbo.

Intercooler upgrades are great for anyone who tracks their Mini or who frequently drives it hard or aggressively on the street. Lastly, E85 mixtures are a good way to get a few extra horsepower for free for those looking to maximize power and performance without upgrading the turbo. If you’re still itching for more power after you’ve implemented all the mods on this list, you’ll want to look towards turbo and fueling upgrades which can help push the Cooper S above 350whp and close to the 400whp the engine is capable of. However, this version of the B48 does have slightly weaker pistons which are likely the first internal component to go kaboom from too much power.

Overall, adding close to 100whp will make the Mini Cooper S a quick and fun car given its size and nimbleness.