Introduction to the Perrin Cold Air Intake for the Subaru BRZ FA20

The Subaru BRZ, with its FA20 flat-four engine, is a driver’s car that responds well to thoughtful modifications. One of the most popular first upgrades is a cold air intake, and the Perrin Cold Air Intake stands out for its engineering quality, filtration performance, and sonic character. By replacing the restrictive factory airbox with a free-flowing intake system, you can reduce intake air temperature, increase airflow volume, and sharpen throttle response. This step-by-step guide takes you through the entire installation, from tools and safety precautions to final tuning considerations. Whether you’re a weekend mechanic or a first-time modifier, following these instructions closely will ensure a clean, leak-free install that delivers reliable gains.

Before we begin, it’s important to understand that while a cold air intake improves performance, the FA20 engine can be sensitive to changes in air-fuel ratios. Many BRZ owners pair an intake like this with an ECUTek or open-source tune to unlock the full horsepower potential. We’ll cover that later. For now, gather your tools, clear your workspace, and prepare to transform your engine bay.

Tools and Materials Needed

Having everything on hand before you start saves time and frustration. Below is a comprehensive list of tools and supplies you’ll need for the Perrin Cold Air Intake installation on a BRZ or Scion FR-S / Subaru BRZ with the FA20 engine. Some items may not be included in the kit; purchase them separately if missing.

  • Socket and ratchet set: 10mm, 12mm, and 14mm sockets (standard and deep well)
  • Torx bits: T25 and T30 (for some trim and sensor screws)
  • Flathead screwdriver (medium sized, for prying clips)
  • Trim removal tool (optional but helpful for plastic fasteners)
  • Torque wrench (5–25 ft-lb range, for proper clamp and bracket tightening)
  • Clean rags or shop towels
  • Electronic contact cleaner (for MAF sensor if reusing)
  • Anti-seize compound (for bolts that might corrode)
  • Zip ties (various sizes, for securing hoses and wiring)
  • Safety glasses and gloves
  • The Perrin Cold Air Intake kit (typically includes intake pipe, air filter, couplers, clamps, bracket, and installation instructions)

If you do not own a torque wrench, consider borrowing one. Over-tightening hose clamps can warp the silicone couplers; under-tightening can cause leaks. A torque wrench set to around 5–7 Nm for hose clamps is ideal.

Preparation Steps

Proper preparation prevents mistakes. Start by parking your BRZ on a level surface and allowing the engine to cool completely. The FA20 engine bay is tight; hot metal and sharp edges can cause burns or cuts. Disconnect the negative battery terminal and move the cable out of the way. This prevents accidental short circuits and resets the ECU so it can learn the new intake parameters.

Open the hood fully and secure it with the prop rod. Remove any loose objects from the engine bay. If your car has an aftermarket strut bar or grounding kit, you may need to temporarily relocate them for access.

1. Remove the Factory Air Intake System

The stock air intake assembly consists of the airbox, intake snorkel, intake tube, MAF sensor housing, and a rubber hose to the engine. Follow these steps:

  • Disconnect the MAF sensor: Unplug the electrical connector from the mass airflow sensor located on the intake tube. Squeeze the locking tab and pull firmly. Do not yank on the wires.
  • Loosen the clamps: Using a flathead screwdriver or 8mm socket, loosen the clamp at the throttle body and the clamp connecting the intake tube to the airbox.
  • Remove the intake tube: Gently wiggle the tube free from the throttle body and airbox. Set it aside.
  • Unbolt the airbox: The stock airbox is held by two 10mm bolts at the bottom and a bracket near the front. Remove them and lift the airbox out. You may need to detach the snorkel that pulls air from the grill – it simply pulls out with moderate force.
  • Clean the area: Use a clean rag to wipe away any dirt or debris near the throttle body opening. If any foreign material falls into the intake, it could damage the engine.

Keep all factory hardware in a bag in case you ever reinstall the stock intake. Do not throw away the MAF sensor – it will be reused with the Perrin intake.

Installing the Perrin Cold Air Intake

Now we move to the main event. The Perrin kit is designed to fit the BRZ/FR-S/86 engine bay with minimal modification. Take time to lay out all parts and confirm no pieces are missing. Refer to the included instruction booklet for any specific notes based on the model year.

2. Assemble the Perrin Intake Pipe and Filter

Perrin uses a mandrel-bent aluminum tube with a smooth interior for maximum airflow. The filter is a dry or oiled cotton gauze type (check your kit). Assemble as follows:

  • Install the filter onto the intake pipe: Slide the included silicone coupler over the pipe’s inlet end, then push the filter onto the coupler and tighten the clamp. Do not tighten fully yet – you will need to rotate the filter for proper clearance.
  • Attach the MAF sensor flange: Some kits include a separate flange that bolts onto the intake pipe; others have a welded bung. If separate, use the provided gasket and screws. Apply a tiny amount of anti-seize to the screws. Make sure the MAF sensor orientation matches the airflow direction arrow (usually indicated on the sensor).
  • Install the mounting bracket: Perrin includes a metal bracket that supports the intake tube. Bolt it loosely to the tube using supplied hardware – do not torque yet.

    • 3. Position and Secure the Intake in the Engine Bay

    Carefully lower the assembled Perrin intake into the engine bay. Route the intake pipe toward the throttle body. Ensure the filter sits in a location where it receives cool, ambient air from the front of the car – the Perrin kit often positions the filter behind the bumper beam or in the fender well, shielded from engine heat.

    • Attach the pipe to the throttle body: Slide the silicone coupler (provided) onto the throttle body opening, then push the intake pipe end into the coupler. Tighten the clamps evenly. Use a torque wrench set to 7 Nm (5 ft-lb) to avoid crushing the silicone.
    • Secure the bracket: The bracket on the intake pipe will align with a factory bolt hole on the engine block or chassis. Use a 12mm bolt (usually included) to fasten it. Tighten to 25 Nm (18 ft-lb).
    • Check clearance: Rotate the filter so it is not touching any hot surfaces, moving parts, or the radiator fan shroud. There should be at least 1 inch of clearance around the filter.
    • Route and secure MAF wiring: Plug the MAF sensor connector back in. Use zip ties to secure the wiring harness away from exhaust components and moving belts. Loose wires can melt or get cut.

    Pro tip: Before final tightening, start the engine briefly (off for safety) to listen for whistles or leaks. If you hear a sucking noise from a coupler, tighten the clamp slightly. A vacuum leak will cause rough idle and a check engine light.

    4. Reconnect Battery and Perform Initial Check

    Reconnect the negative battery terminal and tighten it securely. Clean corrosion from the terminal with a wire brush if needed. Now start the engine. Let it idle for 30 seconds – the idle may be slightly high initially as the ECU relearns. Watch the RPM gauge for stability.

    Turn the steering wheel full lock left and right to ensure the intake does not rub against any steering components. Check all hose connections again after a short heat cycle – silicone couplers can soften and loosen slightly when warm. If everything looks good, take the car for a short test drive.

    Post-Installation Tuning and Calibration

    Why Tuning Matters for the FA20

    The FA20 engine uses a tune-by-wire throttle and advanced fuel mapping. Simply adding a cold air intake may cause the engine to run lean in certain areas unless the ECU is recalibrated. Many BRZ owners report improved throttle response without a tune, but to maximize horsepower and ensure long-term reliability, a custom tune is highly recommended. The Perrin intake alone typically adds 8–12 hp on a dyno with a proper tune. Without a tune, gains are modest but still present.

    Consider using an ECUTek flash tune or open source tuning via Tactrix cable. Professional tuning shops like TuningTechFS offer remote calibrations tailored to the Perrin intake. If you do not tune, drive moderately for the first 100 miles to allow the ECU to adapt. Avoid wide-open throttle until the AFRs are confirmed safe.

    Maintenance and Long-Term Care

    The Perrin filter is reusable. Every 30,000 miles or 12 months (sooner in dusty conditions), clean and re-oil the filter using a kit from Perrin or a compatible brand like K&N. Never use excessive oil – it can coat the MAF sensor and cause false readings. Inspect the silicone couplers for cracks or hardening every two years. Replace clamps if they show rust.

    During routine oil changes, check that all intake connections are tight. If you drive in wet weather, ensure the filter is not positioned where water can be ingested (hydrolock risk). Perrin kits are designed with water resistance in mind, but avoid deep puddles.

    Common Mistakes to Avoid

    • Over-tightening clamps: This can deform silicone couplers and cause permanent leaks. Use a torque wrench.
    • Forgetting to plug in the MAF sensor: The engine will run poorly or stall. Double-check before closing the hood.
    • Leaving the filter too close to the engine: Heat soak reduces performance. Ensure it sits in the cool air path.
    • Using the wrong oil on a dry filter: Some Perrin filters are dry; never oil a filter that is designed to be dry. Check the product label.
    • Skipping ecu adaptation: If you have no tune, resetting the ECU (by disconnecting the battery for 10 minutes after install) can help it learn faster.

    Final Verification and Enjoyment

    After the test drive, park the car and let it cool. Re-check all clamps and the bracket. Look for any codes by reading the OBD-II port with a scanner. If no codes appear, you have successfully completed the installation. The Perrin Cold Air Intake will deliver a deeper, sportier intake note under acceleration and a more responsive throttle. Over time, you may notice improved fuel economy on the highway due to reduced pumping loss.

    For detailed instructions, torque specs, and product updates, always refer to the official Perrin Automotive product page. For community support and installation tips for the BRZ/GT86 platform, the FT86Club forum is an excellent resource with thousands of member experiences.

    Enjoy your upgraded BRZ – every step of this process has been about improving the connection between you and the car. Safe driving.