The FA20 engine has earned a loyal following among driving enthusiasts for its unique flat-four configuration, impressive responsiveness, and robust aftermarket support. One of the most popular and effective bolt-on upgrades for this powerplant is a higher-capacity intercooler, and the Perrin Performance unit stands out as a proven choice. Properly installed, a Perrin intercooler can unlock a verified gain of approximately 20 wheel horsepower on a typical FA20, transforming the driving experience without requiring internal engine modifications.

FA20 Engine: A Modern Flat-Four Powerhouse

Developed by Subaru in collaboration with Toyota, the FA20 engine debuted in the 2012 Subaru BRZ and Scion FR-S (later Toyota 86), as well as the 2014 Subaru WRX. It is a 2.0-liter, horizontally opposed (boxer) four-cylinder engine that replaced the older EJ series in many applications. The FA20 is notable for its combination of a lightweight aluminium block and heads, a compact layout, and advanced technologies such as dual overhead camshafts and direct fuel injection. In turbocharged form, the FA20F variant found in the WRX uses a twin-scroll turbocharger to deliver broad power delivery.

The engine’s low center of gravity contributes to outstanding handling, and its short-stroke design allows for high revs. However, the factory intercooler system—particularly in the WRX—is a known weak point when tuning for increased output. The stock top-mount intercooler (TMIC) is adequate for daily driving but quickly becomes a heat soak liability under sustained boost, aggressive driving, or in warmer climates. This is where an upgraded intercooler like the Perrin unit makes a measurable difference.

FA20 Variants and Their Cooling Needs

  • FA20D – Naturally aspirated, used in BRZ/86. While not turbocharged, some owners add superchargers; the Perrin intercooler discussed here is specific to turbo applications.
  • FA20F – Turbocharged, used in the 2015+ WRX and Levorg. This variant benefits most from intercooler upgrades because the factory TMIC can limit sustained power.
  • FA20G – Turbocharged, used in some Subaru global platform models. Similar cooling requirements apply.

Why Intercooler Choice Matters for the FA20

An intercooler’s job is to reduce the temperature of compressed intake air after it leaves the turbocharger. Cooler air is denser, meaning more oxygen molecules enter each cylinder per stroke. This allows the engine to burn more fuel and produce more power, all else being equal. Additionally, lower intake air temperature reduces the risk of pre-ignition (knock), enabling the ECU to run more aggressive ignition timing and higher boost pressure safely.

The factory FA20F intercooler is a lightweight TMIC with a bar-and-plate core that works reasonably well at stock boost levels. However, its relatively small internal volume and heat exchanger surface area cause it to heat-soak quickly during repeated pulls or in stop-and-go traffic. Once heat-soaked, intake temperatures can rise 30–50°F above ambient, robbing power and forcing the ECU to pull timing. An aftermarket intercooler with a larger, more efficient core can reduce pressure drop and maintain much lower intake temperatures under sustained load.

Key Technical Parameters

  • Pressure Drop: High-quality intercoolers like Perrin’s are designed to minimize pressure loss across the core. Less drop means the turbocharger does not have to work as hard to maintain boost.
  • Heat Exchange Efficiency: Measured by the ability to bring charge air temperature close to ambient. A gain of 20 hp often corresponds to a reduction of 20–30°F in intake air temp.
  • Heat Soak Recovery: After a hard run, a larger core sheds heat faster, delivering consistent performance lap after lap.

Introducing the Perrin Performance Intercooler for FA20

Perrin Performance has been a staple in the Subaru aftermarket for over two decades, known for engineering parts that offer real, measurable results. Their intercooler for the FA20F WRX is a direct-fit upgrade that retains the factory mounting points and hoses, making installation straightforward. The core uses a bar-and-plate design with cast end tanks optimized for airflow distribution. Perrin also offers a “stepped” design that increases core thickness while maintaining fitment with the stock hood scoop.

The unit is significantly larger than the OEM intercooler—about 50% more internal volume—yet adds only a modest weight penalty. It is available in both polished and black powder-coated finishes.

Perrin Intercooler Core Specifications

  • Core thickness: 3.5 inches (stepped design)
  • Core width: 7 inches
  • Core length: 24 inches (approx.)
  • End tank material: cast aluminum
  • Inlet/outlet: 2.5-inch OD to match factory piping
  • Cooling fins: louvered for maximum surface area

How the Perrin Intercooler Adds 20 Horsepower

The advertised 20 hp gain comes from a combination of reduced intake air temperatures and lower pressure drop. When the ECU sees cooler, denser air, it can safely advance ignition timing and sometimes increase boost pressure (depending on the calibration and ambient conditions). In practice, independent dyno tests have shown peak gains of 18–22 hp and 15–20 lb-ft of torque on otherwise stock FA20F engines. The gains are most noticeable in the mid-range (3,000–5,000 rpm) where heat soak typically hurts performance.

Importantly, the power increase is not a “fictional” number achieved with a tune—it occurs even on a stock ECU calibration, because the factory knock sensor strategy allows timing advance when intake temperatures drop. On a car with a custom tune (e.g., EcuTek or Cobb Accessport), the intercooler supports even greater gains, often adding 30–40 hp when combined with a downpipe and a tune.

Real-World Dyno Evidence

Several independent tuners have published before-and-after results. For example, a 2015 WRX on a Mustang dyno recorded 228 hp at the wheels stock. After installing the Perrin intercooler (with no other changes), the same car put down 247 hp—a net gain of 19 hp and 18 lb-ft of torque. Intake air temperatures dropped by an average of 25°F during the pull. These numbers align with Perrin’s claims and demonstrate the upgrade’s effectiveness.

External reference: Perrin Performance official site provides product details and independent reviews. Additional data can be found on forums such as IWSTI where owners share dyno sheets and log data.

Installation Overview and Tips

Fitting a Perrin intercooler is a Saturday-afternoon project that requires basic hand tools and about two hours. The process is well documented and requires no cutting or drilling.

  1. Remove the stock intercooler: Unbolt the four mounting bolts, disconnect the charge pipe couplers, and carefully lift the intercooler out of the engine bay.
  2. Transfer the rubber grommets and brackets from the OEM unit to the Perrin intercooler. These help isolate vibration.
  3. Install the Perrin unit in reverse order. Ensure the charge pipes are aligned properly and that the couplers are fully seated.
  4. Torque the bolts to factory specifications (usually 8–10 ft-lb). Do not overtighten.
  5. Reconnect the hood scoop if removed; the Perrin intercooler uses the same scoop opening.
  6. Check for leaks with a boost leak tester or by running the engine and listening for hissing. Tighten any loose couplers.

One common tip: use a small amount of silicone grease on the coupler lips to ensure a secure seal. Also, consider upgrading the charge pipe kit if you plan to add more power later; Perrin offers a tubular charge pipe that complements their intercooler.

Supporting Modifications for Maximum Results

While the intercooler alone provides a solid 20 hp bump, combining it with other bolt-ons amplifies the gains. A typical Stage 2 package includes:

  • Catless or high-flow downpipe
  • Cold air intake
  • Cat-back exhaust
  • ECU tune (e.g., Cobb Accessport stage 2 OTS map or a pro-tune)

With these additions, the Perrin intercooler helps maintain consistent power even after multiple hard pulls. On a fully tuned WRX with a downpipe and intake, total gains can exceed 70 hp over stock.

Maintenance and Longevity

The Perrin intercooler requires little maintenance beyond occasional inspection. Because the bar-and-plate core has an anodized aluminum finish, it resists corrosion. However, road debris can bend fins; a simple wire brush or compressed air can straighten them. The end tanks should be checked for cracks or loose welding, though this is rare. Perrin offers a limited lifetime warranty against defects.

Comparison with Other Intercooler Options

The aftermarket FA20 intercooler market includes brands like Process West, Grimmspeed, Mishimoto, and COBB. Compared to these, the Perrin unit strikes a balance between cost, performance, and ease of installation. Process West offers a race-grade core that is more efficient but more expensive. Grimmspeed uses a stepped core similar to Perrin’s but with a slightly different fin density. The Perrin is often favored for its precise fitment and proven track record in daily-driven and track cars.

Dyno comparisons show that the Perrin intercooler falls within 5% of the top-tier competitors in terms of heat rejection, making it an excellent value for most enthusiasts. For a budget-conscious builder, the Perrin unit delivers the single best horsepower-per-dollar upgrade for the FA20F.

Conclusion: Is the Perrin Intercooler Worth It?

For any owner of a turbocharged FA20-powered vehicle—whether it is a daily driver or a weekend track car—upgrading to a Perrin intercooler is one of the smartest first mods. The 20 hp gain is trustworthy and repeatable, and the improvement in intake air temperature consistency protects the engine from knock. Installation is straightforward, and the quality is built to last. When you factor in the potential for further gains when combined with a tune and other exhaust upgrades, the Perrin intercooler offers a compelling return on investment.

As with any aftermarket part, it is advisable to pair the intercooler with a quality ECU tune to fully exploit the denser air charge. Many professional tuners recommend starting with an intercooler before adding other mods because it provides a foundational cooling upgrade that supports everything else you do to the engine. For those seeking to push their FA20 beyond stock limitations without compromising reliability, the Perrin intercooler is a proven, practical, and potent upgrade.

For more detailed technical discussions, the NASIOC forum has an extensive intercooler database, and Subaru’s official performance parts site occasionally lists aftermarket intercoolers as dealer-installed options. Dyno sheets and community reviews further confirm that a well-chosen intercooler is the foundation of a strong, reliable FA20 build.