How to Upgrade Your Subaru’s Turbocharged Engine with an External Wastegate for Better Performance

If you’re a Subaru owner looking to optimize your turbocharged engine’s performance, you may want to consider upgrading your internal wastegate to an external one. An external wastegate can provide a range of benefits, including increased boost control and more efficient exhaust-gas pressure management, which ultimately results in a better-performing engine.

In this article, we’ll show you how to make an internal wastegate external on your Subaru. We’ll cover everything from the benefits of upgrading to the types of wastegates available, the tools required for the installation process, the steps involved in modifying the system, and useful tips and tricks to ensure a successful installation.

Advantages of an External Wastegate Upgrade

Before we dive into the installation process, let’s take a look at the benefits of upgrading your internal wastegate to an external one. The primary advantage of using an external wastegate is the increase in boost control, which significantly improves engine performance. When the exhaust gas reaches a specific pressure, the internal wastegate valve opens. However, this valve can be restrictive, limiting the turbocharger’s boost pressure, and ultimately, engine performance.

External wastegates solve this problem by relocating the valve outside of the turbocharger system. The increase in boost pressure control and improved efficiency of regulating exhaust gas increases the turbocharger’s lifespan. The wastegate can also eliminate boost creep, providing smoother and safer operation of the turbo system.

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Types of Wastegates

There are two common types of wastegates: internal and external. The internal wastegate is located inside the turbocharger housing, while the external wastegate is located outside of the turbocharger. For an external wastegate, there are two types, a single-port and a dual-port. In general, the dual-port wastegate provides more precise boost control, which results in better turbo response and performance.

Tools Required

To install an external wastegate, you’ll need a few basic tools, including:

  • Wastegate actuator
  • Wastegate flange
  • Vacuum hose
  • Boost gauge
  • 10mm socket set
  • Turbo outlet gasket
  • Turbo inlet gasket
  • Exhaust manifold gasket
  • Copper gasket maker
  • Welder or exhaust fabrication facility.

Steps Involved in Modifying the System

Now that we’ve covered the advantages of an external wastegate and the tools required for the task let’s move for the installation procedure:

  1. First, remove the turbocharger and exhaust manifold from the engine. Then locate the internal wastegate, typically located on the turbocharger’s underside.
  2. Remove the internal wastegate actuator and replace it with the new external wastegate actuator. Make sure to attach the correct rod to the wastegate diaphragm and wastegate arm. Use the copper gasket maker provided to seal the external wastegate actuator to the flange.
  3. Weld the external wastegate flange to the exhaust manifold.
  4. Once the external wastegate is mounted, connect the vacuum hose from the actuator to the vacuum source on the intake manifold.
  5. Install the boost gauge to monitor boost pressure and avoid over-boosting your engine.
  6. Reassemble the turbocharger and exhaust manifold to the engine. Be sure to replace the turbo inlet and outlet gaskets and the exhaust manifold gasket.
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Useful Tips and Tricks

  • It’s essential to choose the correct wastegate size to avoid over/under boosting, which can lead to engine damage.
  • Before making any modifications, consult your car’s owner’s manual or an experienced mechanic.
  • It’s best to seek advice from trusted car enthusiasts or automotive online resources for more information on wastegates.
  • A professional welder will be better suited for the welding process than attempting a DIY job if you lack experience.


Q. Do you need to upgrade the internal wastegate to an external one?

A. No, you don’t have to upgrade your internal wastegate to an external wastegate. However, an external wastegate provides better boost control, improves engine performance, eliminates boost creep, and prolongs the life of the turbocharger.

Q. How much boost pressure can an external wastegate manage?

A. External wastegates can manage pressure up to 60 psi. However, the pressure varies depending on the type of wastegate and engine modification.

Q. Can you install an external wastegate yourself?

A. Installing an external wastegate is relatively simple; however, it requires technical know-how and tools such as a welder. If you’re unsure or have not had any experience, we recommend consulting a professional mechanic.


An external wastegate upgrade is an excellent way to improve the performance of your Subaru engine. It’s a relatively straightforward process that can result in better boost pressure control, increased turbocharger lifespan, and, ultimately, better engine performance. With the right tools and knowledge, you can complete the installation process yourself or consult a professional to help you. Remember, before making any modifications to your engine, consult your mechanic or car’s owner’s manual.

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Davis Bellew

As a Subaru owner and enthusiast, Davis has a deep understanding of the needs and concerns of Subaru drivers. He specializes in writing informative and engaging content about Subaru maintenance and repair, and his articles are always well-researched and easy to understand. When he's not writing, he enjoys hiking and photography.

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