Introduction: Why Upgrade to Perrin Equal Length Headers?

The Subaru BRZ (and its twins, the Toyota GR86 and Scion FR-S) is already a driver’s car from the factory, but its naturally aspirated boxer engine leaves room for improvement in both power delivery and exhaust character. One of the most effective bolt-on modifications for the FA20 engine is a set of equal length headers. Perrin Performance, a well-known name in Subaru aftermarket, offers a premium equal length header designed specifically for the BRZ platform. Unlike the factory unequal length headers that produce the classic Subaru “boxer rumble,” these equal length tubes prioritize exhaust scavenging and flow efficiency. The result is a noticeable bump in mid-range and top-end horsepower, a cleaner sound profile with reduced drone, and improved throttle response. This article takes an in-depth look at the sound characteristics, dyno-verified performance gains, and practical installation tips for the Perrin Equal Length Headers. Whether you are a weekend DIYer or a seasoned tuner, this guide will help you decide if this upgrade fits your build.

Sound Characteristics: From Rumble to Refinement

The most immediately noticeable change after fitting Perrin Equal Length Headers is the transformation of the exhaust note. Many enthusiasts choose equal length headers specifically because they alter the classic Subaru rumble. Here is a breakdown of what to expect.

Tonal Shift and Frequency

Factory unequal length headers (UEL) fire cylinders at uneven intervals, producing the iconic off-beat rumble that Subaru fans love. Perrin’s equal length design balances exhaust pulses, creating a smoother, more even firing order. Instead of the staccato “burble,” you will hear a refined, linear note that leans toward a higher-frequency scream at high RPM. Many describe it as closer to a Honda K-series or a Porsche flat-six — still distinctly boxer, but more civilized. The equal length headers also eliminate much of the low-frequency drone that can make long highway drives fatiguing with UEL headers. At cruising speeds, cabin noise drops significantly, making the BRZ a more pleasant daily driver.

Volume and Aggression

Perrin’s headers do not necessarily make the exhaust louder overall; they shift the volume peak higher in the rev range. With an otherwise stock exhaust, the headers add about 3–5 dB at full throttle above 5,000 RPM, but the sound is cleaner and less harsh. When paired with a catback or axleback exhaust system, the tone becomes more aggressive without becoming obnoxious. The reduced drone is a major selling point for those who want a sporty sound without the headache of constant resonance.

Real-World Sound Clips

While subjective, many YouTube reviews and forum clips show that the Perrin Equal Length Headers produce a pronounced induction noise (especially when combined with an aftermarket intake) and a crisp exhaust note that rewards revving the engine. The sound is less “muscular” than UEL headers but more precise and exotic. For track use, this can help with auditory feedback — you can hear the engine building power smoothly rather than drowning in low-frequency noise.

Performance Gains: Dyno-Proven Horsepower and Torque

Perrin’s engineering focus on scavenging and flow is validated by dyno results from independent tuners. The FA20 engine responds well to reduced backpressure and optimized exhaust gas velocity. Using a quality equal length header like the Perrin unit can yield measurable gains across the powerband.

Dyno Numbers: What to Expect

On a bone-stock BRZ, replacing the factory headers with Perrin’s equal length headers typically nets 10–15 horsepower at the wheels (whp) and 8–12 lb-ft of torque. The peak gain occurs around 6,500–7,000 RPM, with a significant improvement from 4,500 RPM to redline. Torque does not drop off as sharply after peak, flattening the curve and maintaining pull past 7,000 RPM. For example, a car making 175 whp stock may hit 187–190 whp with a catback exhaust and Perrin headers — a solid gain before tuning.

Mid-Range vs Top-End

Compared to UEL headers, equal length headers like Perrin’s sacrifice a small amount of low-end torque (below 3,500 RPM) for strong mid-range and top-end gains. Many drivers report that the car feels livelier from 4,000 RPM upward, making it more enjoyable for canyon carving and track days. The improved scavenging also helps maintain power through gear shifts, reducing the sensation of “falling off the cam.”

Compatibility with Other Mods

These headers shine when paired with a full exhaust system (aftermarket catback, high-flow front pipe, or even a tune). With an off-the-shelf tune (Stage 2), gains can reach 20–25 whp. The headers also reduce exhaust gas temperatures (EGT) slightly, which is beneficial for track use and longevity when running aggressive ignition timing. It is worth noting that the Perrin headers are 50-state legal (carb EO) for emissions compliance, though check local laws regarding catalyst location.

Installation Tips: A Step-by-Step Approach

Installing headers on a BRZ is a moderately difficult job, but with the right tools, patience, and these tips, many DIYers can complete it in a weekend. Perrin provides a detailed instruction manual, but here are the most critical considerations.

Required Tools and Supplies

  • Socket set (metric, including 10mm, 12mm, 14mm, 17mm, 19mm)
  • Wrenches (combination and ratcheting)
  • Torque wrench (ft-lb and in-lb)
  • Pry bar or long flathead screwdriver for stubborn exhaust hangers
  • Penetrating oil (e.g., PB Blaster) for rusty bolts
  • Replacement exhaust gaskets (Perrin includes new ones, but have spares)
  • High-temperature anti-seize compound for bolts
  • Jack and jack stands (or a lift)

Step-by-Step Overview

  1. Preparation: Disconnect the negative battery terminal to avoid accidental electrical issues. Raise the vehicle securely on jack stands. Allow the exhaust to cool completely to avoid burns.
  2. Remove OEM Headers: Unbolt the factory headers from the cylinder head (typically 10 nuts, 12mm). Remove the front pipe and catalytic converter assembly — this may require unbolting the downpipe from the midpipe and dealing with stubborn O2 sensors. Use penetrating oil on the O2 sensor threads to avoid stripping.
  3. Transfer O2 Sensors: Perrin headers have bungs for the upstream and downstream O2 sensors. Carefully unscrew the sensors from the factory pipes and reinstall them into the new headers. Use anti-seize on the threads, but avoid getting it on the sensor tip.
  4. Fit the Perrin Headers: With the old headers removed, position the new unit. Start all nuts and bolts by hand to avoid cross-threading. Perrin’s design includes a flex joint to accommodate engine movement — do not overtorque the flex joint bolts.
  5. Tighten in Sequence: Torque the header-to-head nuts to ~32 ft-lb (check Perrin’s spec) in a crisscross pattern. Tighten the collector bolts and the front pipe flange bolts. Reuse the factory spring bolts or use new hardware supplied.
  6. Reconnect Exhaust Hangers: Use pliers or a hanger tool to reattach the rubber hangers for the catback section. Ensure no components touch the chassis or steering shaft.
  7. Double-Check Clearances: Crank the engine (with ear protection) and check for leaks. Use a stethoscope or listen for hissing. Also check that the headers do not contact the oil pan, subframe, or front sway bar. In some cases, you may need to slightly loosen and reposition the driver-side mount.
  8. Test Drive and Retorque: After a short heat cycle, let the car cool and retorque all bolts. Metal gaskets compress, so re-tightening after 50–100 miles is recommended.

Common Pitfalls and Solutions

  • O2 Sensor Access: The downstream O2 sensor can be tight against the transmission tunnel. A crowsfoot wrench or offset O2 sensor socket helps. Consider extending the harness if needed.
  • Heat Management: The Perrin headers are uncoated 304 stainless steel, which radiates considerable heat. Consider wrapping the headers with thermal wrap or applying a ceramic coating to reduce underhood temperatures and protect engine mounts, wiring, and the starter.
  • Bolt Seizure: FA20 header bolts are prone to rusting. Soak them overnight with penetrating oil. If a nut strips, use a bolt extractor or cut it off with a Dremel.
  • Engine Mount Clearance: Some users report slight contact with the driver-side engine mount bracket. A common fix is to loosen the engine mount, shift the engine slightly toward the passenger side, and retighten. Alternatively, use a small washer to space the header flange.

Tuning Considerations: Unlocking Full Potential

While the headers produce gains without a tune, a proper ECU calibration (usually a Stage 1 or Stage 2 tune) will maximize power, smooth out the air/fuel ratios, and eliminate any check engine light for catalyst efficiency. The FA20 runs lean from the factory in certain areas, and headers increase flow — an off-the-shelf tune from reputable tuners like Delicious Tuning, OFT (OpenFlash Tablet), or Ecutek calibrators can add another 5–10 hp. Tuning also allows you to adjust for individual exhaust setups (catless vs catted) and unlock better throttle mapping.

If you are using a catless front pipe with the Perrin headers, you will almost certainly need a tune to prevent the check engine light and to avoid excessive exhaust soot. Many tuners offer a “header tune” that raises the idle slightly to prevent stalling and adjusts timing for optimal torque. Expect to spend $500–$700 for a professional tune plus the cost of the tablet or software.

Longevity and Maintenance

Perrin uses T304 stainless steel, which resists corrosion and thermal fatigue well. The welds are TIG-quality and have held up over many track seasons. However, stainless steel headers can blue (discolor) over time due to heat — this is cosmetic. To extend the life of the headers, retorque bolts every 10,000 miles and inspect for cracks near the welds, especially if the car sees frequent track use. Applying a coat of high-temperature silver paint or ceramic coating before installation helps prevent discoloration and improves heat retention in the exhaust system. Expect the headers to last the lifetime of the engine with normal maintenance.

Conclusion: A Worthwhile Upgrade for Enthusiasts

Perrin’s Equal Length Headers for the Subaru BRZ deliver on their promises: noticeable horsepower and torque gains, a refined exhaust note with reduced drone, and improved throttle response. The installation is manageable for a confident DIYer with the right tools, and tuning unlocks additional potential. While the loss of the traditional Subaru rumble may disappoint some purists, the trade-off in performance and daily drivability is compelling. For those who track their cars, enjoy a smoother powerband, or simply want a high-quality equal length header from a trusted brand, Perrin’s offering is a top contender. Pair them with a good exhaust and tune, and your BRZ will feel like a completely different car — one that revs more freely, sounds more exotic, and pulls harder to redline.