For owners of turbocharged Subaru models, upgrading the exhaust system is one of the most impactful modifications you can make. A thoughtfully chosen exhaust not only improves engine efficiency and increases horsepower but also enhances the signature Subaru sound that enthusiasts cherish. Whether you're aiming for better turbo spool, a more aggressive exhaust note, or improved fuel economy, the right exhaust upgrade can transform your driving experience.

Why Upgrade Your Subaru Exhaust System?

Turbocharged Subaru engines, such as those in the WRX, STI, and Forester XT, rely heavily on efficient exhaust flow to maximize performance. The factory exhaust systems are often designed with noise regulations and cost considerations in mind, which can limit their ability to optimize power and sound. Upgrading your exhaust system addresses several key areas:

  • Reduced Backpressure: Stock exhausts tend to create backpressure that restricts the flow of exhaust gases. High backpressure reduces the turbocharger’s efficiency by slowing down exhaust gas evacuation, which in turn delays turbo spool and reduces power output. An upgraded exhaust system typically features larger diameter piping and smoother bends to minimize backpressure and promote better exhaust scavenging.
  • Improved Turbo Response: A freer-flowing exhaust allows the turbo to spool faster, improving throttle responsiveness and reducing turbo lag. This translates to more immediate power delivery, particularly noticeable in mid-range RPMs where turbo boost is crucial.
  • Horsepower and Torque Gains: By enhancing exhaust flow and reducing restrictions, aftermarket exhausts can unlock additional horsepower and torque. Gains vary depending on the system and supporting modifications but can range from 5 to 15 horsepower or more.
  • Enhanced Sound Profile: Subaru turbocharged models are known for their distinctive boxer engine rumble and turbo whistle. Upgraded exhaust systems amplify these characteristics, offering a deeper, more aggressive tone that can be tailored to your preferences, from a subtle growl to a throaty roar.
  • Weight Reduction: Many aftermarket exhausts use lightweight materials such as high-grade stainless steel or titanium, reducing overall vehicle weight and improving handling.
  • Durability and Longevity: Quality aftermarket exhausts often use corrosion-resistant materials and superior welds, ensuring longer life and maintaining performance over time, especially in harsh weather conditions.

Understanding Subaru Exhaust System Components

Before selecting an exhaust upgrade, it’s important to understand the different components typically involved:

  • Downpipe: The section of exhaust piping that connects directly to the turbocharger outlet. Upgrading the downpipe can drastically improve exhaust flow and turbo spool since it handles hot, high-pressure gases exiting the turbo.
  • Midpipe: Connects the downpipe to the rest of the exhaust system. Some systems combine the downpipe and midpipe for fewer restrictions.
  • Cat-back Exhaust: This refers to the exhaust components from the catalytic converter back to the muffler and tailpipe. Cat-back systems are popular upgrades as they improve flow without affecting emissions controls.
  • Muffler: Responsible for controlling noise, mufflers can be designed for different sound levels and tones, affecting the overall exhaust note.
  • Catalytic Converter: Some enthusiasts upgrade to high-flow catalytic converters or remove them entirely (where legal) to reduce restrictions, but this can impact emissions compliance and legality.

Top Exhaust Systems for Turbocharged Subaru Models

1. Borla Exhaust Systems

Borla is a renowned name in the exhaust industry, known for manufacturing premium quality systems with a focus on performance and longevity. Their systems are constructed from high-grade stainless steel and feature mandrel-bent tubing for optimal flow. Borla’s cat-back exhausts for Subaru turbo models like the WRX and STI deliver a deep, aggressive exhaust note without being overly loud or drone-prone.

Key Features:

  • High-quality T-304 stainless steel construction
  • Mandrel-bent tubing for smooth exhaust flow
  • Patented straight-through muffler design for balanced sound and performance
  • Corrosion-resistant finish for durability
  • Easy bolt-on installation with no modifications required

Performance Impact: Users report up to a 10-12 horsepower gain with Borla cat-back systems, along with noticeably improved turbo spool and throttle response. The sound is sporty and aggressive, ideal for daily driving and spirited runs.

2. Cobb Tuning Exhaust

Cobb Tuning is a brand deeply rooted in Subaru performance culture. Their exhaust systems are engineered specifically for Subaru turbocharged models, ensuring perfect fitment and maximizing airflow. Cobb offers several exhaust options, including cat-back and downpipe systems, designed to complement their tuning software and other performance parts.

Key Features:

  • High-quality stainless steel construction
  • Precision fitment tailored for Subaru WRX and STI models
  • Multiple muffler options ranging from subtle to aggressive tones
  • Optimized for improved turbo response and power gains
  • Designed to work seamlessly with Cobb’s Accessport tuning system

Performance Impact: Cobb exhausts typically yield horsepower increases in the 8-15 hp range and enhance turbo spool characteristics. The sound can be customized via different muffler options, allowing drivers to choose their preferred exhaust tone.

3. Invidia Exhaust Systems

Invidia is a favorite among Subaru enthusiasts for their blend of performance, sound, and affordability. Their stainless steel exhausts are known for robust construction and a rich exhaust note. The Q300 and R400 lines are especially popular for turbocharged Subaru models.

Key Features:

  • 304 stainless steel construction with high-temperature polished finish
  • Mandrel-bent piping and TIG welding for durability and flow
  • Q300 line offers a moderate sound level with smooth tone
  • R400 line provides a louder, more aggressive exhaust note for enthusiasts seeking maximum presence
  • Cat-back and downpipe options available

Performance Impact: Invidia exhaust systems provide noticeable gains in turbo response and horsepower, typically around 7-12 hp depending on the model and supporting mods. The exhaust tone is highly praised for its deep, throaty growl that enhances the Subaru boxer character.

4. Grimmspeed Exhaust Systems

Grimmspeed has a strong reputation in the Subaru tuning community, offering both downpipes and cat-back exhausts designed for performance and reliability. Their products are engineered to optimize turbocharged engine efficiency, with an emphasis on improving spool time and power delivery.

Key Features:

  • 304 stainless steel construction
  • Mandrel-bent piping for consistent flow
  • Options for cat-back and downpipe upgrades
  • Designed to complement aftermarket turbo upgrades and tuning
  • Sound profile ranges from moderate to aggressive depending on the chosen system

Performance Impact: Grimmspeed exhausts can help reduce turbo lag and increase horsepower by up to 10 hp. Their systems are popular for daily-driven Subarus that need a balance of sound, power, and emissions compliance.

5. TOMEI Expreme Ti Exhaust Systems

For enthusiasts who want to combine performance with weight savings, TOMEI’s titanium exhaust systems offer an exceptional option. Although pricier, these exhausts are ultra-lightweight and designed for maximum flow and aggressive sound.

Key Features:

  • Lightweight titanium construction
  • Mandrel-bent piping with smooth bends
  • Exotic, aggressive exhaust note
  • Reduced heat retention for improved engine bay temperatures
  • Designed primarily for track and high-performance street applications

Performance Impact: TOMEI exhausts provide excellent gains in power and turbo response, along with significant weight reduction compared to steel systems. Their sound is loud and aggressive, ideal for serious performance enthusiasts.

Factors to Consider When Choosing an Exhaust System

Choosing the best exhaust for your turbocharged Subaru depends on several important factors. Consider the following to ensure you select a system that aligns with your goals:

  • Material: Stainless steel is the most common choice due to its durability and corrosion resistance. Titanium offers weight savings but at a premium price. Mild steel is less durable and prone to rust.
  • Sound Level and Tone: Decide whether you want a subtle exhaust growl suitable for daily driving or a loud, aggressive tone that stands out. Some systems offer interchangeable muffler options or adjustable valves to tailor sound.
  • Performance Objectives: Are you looking for maximum horsepower gains, improved turbo spool, or just a better sound? Systems that include downpipe upgrades generally offer greater power improvements.
  • Emissions Compliance: Check local regulations regarding catalytic converter removal or high-flow cats. Some exhaust upgrades may not be street legal in certain regions.
  • Installation Complexity: Cat-back systems usually bolt on without issues, while downpipes may require professional installation and additional supporting modifications.
  • Compatibility: Ensure the exhaust is designed for your specific Subaru model and year, as fitment can vary between WRX, STI, Forester XT, and others.
  • Budget: Performance exhausts vary widely in price. Consider how much you’re willing to invest and balance cost against performance and durability.

Installation Tips and Considerations

Proper installation is key to maximizing the benefits of your new exhaust system. Here are some tips:

  • Professional Installation: If you’re not experienced with exhaust work, consider professional installation to ensure proper fitment and avoid leaks.
  • Gasket and Hardware Replacement: Always replace gaskets and hardware when installing a new exhaust to prevent leaks and ensure a secure fit.
  • Check for Clearance: Make sure the exhaust has adequate clearance from suspension components and the underbody to prevent rattling or damage.
  • Retune After Installation: For turbocharged engines, an ECU tune after installing a freer-flowing exhaust can help optimize air/fuel ratios and maximize power gains.
  • Inspect for Leaks: After installation, check for exhaust leaks at all connection points to maintain performance and prevent unwanted noise.

Maintaining Your Upgraded Exhaust System

To preserve the performance and longevity of your upgraded exhaust, regular maintenance is essential:

  • Periodic Inspection: Check for rust, cracks, or loose bolts periodically, especially if you drive in wet or salty conditions.
  • Cleaning: Use mild soap and water to clean stainless steel or titanium exhausts. Avoid abrasive cleaners that can damage finishes.
  • Heat Cycling: After installation, allow the exhaust to heat cycle (warm up and cool down) a few times to help the metal settle and prevent premature cracking.
  • Addressing Noise Issues: If you experience excessive drone or noise, consider adding resonators or adjusting muffler components where possible.

Conclusion

Upgrading the exhaust system on your turbocharged Subaru is one of the most rewarding modifications you can make. Whether you choose a Borla cat-back for refined aggression, a Cobb Tuning exhaust for performance synergy, or an Invidia system for deep tone and reliability, the right exhaust will enhance your vehicle’s power, turbo response, and iconic Subaru sound.

Remember to consider your performance goals, sound preferences, compatibility requirements, and local emissions regulations when selecting an exhaust. With proper installation and maintenance, your upgraded exhaust will provide years of enhanced driving enjoyment and make your Subaru stand out on the road or track.