Mastering Turbo Subaru Tuning: A Comprehensive Guide for Maximizing Performance and Power

Subaru cars are known for their reliability, performance, and ease of customization. If you own a turbocharged Subaru, you are in for a treat. Turbocharging can boost the power output of your Subaru and provide you with an exhilarating driving experience.

However, tuning a turbocharged Subaru requires skill, knowledge, and patience. In this comprehensive guide, we will show you how to tune your turbo Subaru for optimal performance and power. Whether you are a Subaru enthusiast looking to upgrade your car or a novice tuner, this guide is for you.

Understanding Turbocharging

Before we dive into tuning your Subaru, let’s understand how turbocharging works. A turbocharger is a forced induction system that increases the airflow into a car’s engine. The turbocharger consists of a turbine and a compressor mounted on a common shaft. The turbine is driven by exhaust gases, which spin the compressor and force air into the engine.

The increased airflow into the engine allows for more fuel to be burnt, resulting in increased power output. However, this also generates more heat, which can cause engine problems if not well managed.

Types of Turbochargers

There are two types of turbochargers commonly used in Subaru cars: the journal bearing turbo and the ball bearing turbo.

The journal bearing turbo is the most common type and is used in most factory turbocharged Subaru cars. It is reliable, affordable, and easy to replace. However, it has some limitations in terms of power output and responsiveness.

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The ball bearing turbo, on the other hand, is more advanced and provides better performance and responsiveness. It uses ball bearings instead of journal bearings, which reduce friction and provide quicker spool times. However, it is more expensive than the journal bearing turbo.

Upgrading Turbo Subarus

If you want to upgrade your turbo Subaru, there are multiple options available. You can either replace the turbocharger or upgrade the existing one with aftermarket parts.

When selecting a new turbocharger, consider factors such as the size, compressor map, and exhaust housing. A bigger turbocharger will provide more power, but it may also cause turbo lag and affect the drivability of the car. A smaller turbocharger, on the other hand, will spool quickly but may not reach the desired power output.

Upgrading the existing turbocharger with aftermarket parts such as a larger compressor wheel or a high-flow turbine will also increase power output. However, be careful not to exceed the maximum allowable boost pressure, as this can cause engine damage.

Tuning the ECU

Tuning the ECU, or Engine Control Unit, is an integral part of turbo Subaru tuning. The ECU controls the engine’s fuel injection, ignition timing, and other parameters to optimize performance and efficiency.

There are two types of ECU tuning: piggyback tuning and standalone tuning. Piggyback tuning involves adding an external unit to the ECU, which intercepts signals and modifies them. Standalone tuning involves replacing the factory ECU with an aftermarket one, which provides more control and flexibility.

Both types of tuning require advanced knowledge and experience. It is recommended to seek the help of a professional tuner to ensure optimal results.

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Exhaust Systems

Upgrading the exhaust system is another way to improve the performance of your turbo Subaru. A high-performance exhaust system reduces backpressure, increases exhaust flow, and provides a deeper exhaust note.

There are two types of exhaust systems: axle-back and cat-back. Axle-back systems replace the mufflers and resonators located after the rear axle, while cat-back systems replace everything from the catalytic converter to the exhaust tips.

When selecting an exhaust system, consider factors such as the material, size, and sound level. A larger exhaust diameter will increase exhaust flow, but it may also cause resonance and droning.

Common Mistakes to Avoid

Tuning a turbocharged Subaru requires attention to detail and patience. Here are some common mistakes to avoid during the tuning process:

  • Overboosting: Exceeding the maximum allowable boost pressure can cause engine damage and reduce reliability.
  • Running lean: A lean air/fuel ratio can cause detonation and engine damage. Make sure to monitor the air/fuel ratio and adjust as necessary.
  • Using poor quality fuel: Using low-quality fuel can cause engine knock and reduce performance. Use high-quality fuel with a rating suitable for turbocharged engines.

Frequently Asked Questions

How much power can I expect from a tuned turbo Subaru?

The power output of a tuned turbo Subaru depends on multiple factors, such as the type of turbocharger, exhaust system, and ECU tuning. However, most turbo Subaru’s can reach power outputs of 300-400 horsepower with the right upgrades and tuning.

Can I tune my turbocharged Subaru myself?

Tuning a turbocharged Subaru requires advanced knowledge and experience. It is recommended to seek the help of a professional tuner to ensure optimal results.

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Are there any downsides to upgrading my turbo Subaru?

Upgrading your turbo Subaru can cause increased wear and tear on the engine and drivetrain components. It can also reduce reliability if not done correctly. Make sure to carefully select the right upgrades and seek the help of a professional tuner.


Tuning a turbocharged Subaru can provide an exhilarating driving experience and increase power output. However, it requires advanced knowledge, experience, and patience. In this comprehensive guide, we covered the basics of turbocharging, the different types of turbochargers, and how to select the right upgrades. We also covered ECU tuning, exhaust systems, and common mistakes to avoid. Follow these tips and seek the help of a professional tuner to optimize your turbo Subaru’s performance and power.

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Peter Banks

With years of experience as a professional mechanic and Subaru specialist, Peter is one of the most respected members of our team. He's written several articles on Subaru maintenance and repair, and his advice and tips are always practical and helpful. When he's not working on cars, he enjoys cooking and trying out new recipes.

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