Understanding Headers and Their Role in Subaru BRZ Performance

Headers, also known as exhaust manifolds, are a critical component of any internal combustion engine’s exhaust system. On the Subaru BRZ, the headers are responsible for collecting exhaust gases from each cylinder and channeling them into the exhaust piping. The design and material of the headers directly influence exhaust flow, engine scavenging, and ultimately, performance and sound. Factory headers are typically cast iron or thin-walled tubing designed for cost efficiency, emissions compliance, and a quiet operation. Aftermarket headers like those from Grimmspeed replace these restrictive units with larger, smoother tubes that reduce backpressure and improve cylinder evacuation. For the BRZ’s FA20 engine, which is known for its boxer configuration and relatively flat torque curve, a properly designed header can unlock additional power and a significantly more engaging exhaust note.

The Subaru BRZ is widely regarded as a modern entry-level sports car, praised for its balanced chassis and driver-focused dynamics. However, many owners find the stock exhaust note too subdued, and the engine’s power delivery somewhat linear. Upgrading headers is one of the most common modifications because it addresses both the sound and the performance ceiling. By allowing the engine to breathe more freely, headers can increase peak horsepower by 10–20 wheel horsepower and improve throttle response across the rev range. This article provides an in-depth sound test comparison between the Grimmspeed headers and the OEM headers installed on a 2022 Subaru BRZ, along with performance data, installation insights, and real-world driving impressions.

Grimmspeed Headers for the Subaru BRZ: Detailed Overview

Grimmspeed is a well-respected manufacturer within the Subaru aftermarket community, known for precision-engineered components that balance performance and reliability. Their BRZ headers are constructed from 304-grade stainless steel, offering excellent corrosion resistance and heat tolerance. The headers feature a tubular design with equal-length primary runners, which optimizes exhaust pulse timing and minimizes backpressure. This design not only improves power but also produces a distinctive, smooth exhaust note that differs from the uneven pulses of some other header styles.

Key Features of Grimmspeed Headers

  • Material: 304 stainless steel, 1.5-inch primary tubes, and 2.5-inch outlet diameter.
  • Welds: TIG-welded with smooth internal transitions for minimal flow restriction.
  • Fitment: Direct bolt-on replacement for FA20 engines (Subaru BRZ, Scion FR-S, Toyota 86).
  • Heat Management: Header is designed to accept OEM heat shields; optional thermal wrap or coating can be added for under-hood temperature reduction.
  • Emissions: Includes provisions for oxygen sensor bungs (both upstream and downstream), though a tune is typically required to avoid a check engine light when replacing the OEM unit.

Grimmspeed also offers a ceramic-coated version (powder coating) that further reduces under-hood temperatures and improves thermal efficiency. Independent dyno testing shows peak gains of 12–15 wheel horsepower on a stock BRZ when paired with a proper ECU tune. The headers come with a limited lifetime warranty, reflecting the company’s confidence in their build quality.

OEM Headers: Design Constraints and Sound Profile

The factory headers on the Subaru BRZ are a compact, log-style manifold made from cast stainless steel. They are optimized for cold-start emissions, fuel efficiency, and quiet operation—not for maximum power. The OEM headers incorporate a built-in catalytic converter integrated into the manifold itself (a trend common in modern cars to reduce weight and cost). This integrated catalyst restricts flow, especially at higher RPMs, and dampens the engine’s natural sound. As a result, the BRZ’s stock exhaust note is often described as “muted” or “flat,” with little of the boxer rumble enthusiasts crave.

Characteristics of OEM Headers

  • Material: Cast stainless steel with integrated catalytic converter.
  • Flow: Restrictive by design to meet emissions standards; small-diameter runners limit high-RPM power.
  • Sound: Subdued and quiet, even when revved. The integrated cat reduces rasp and volume.
  • Weight: Approximately 8.5 lbs (3.9 kg) including the cat – heavier than many aftermarket options.
  • Cost: High replacement cost if damaged—OEM part can exceed $600 from a dealer.

While the OEM headers are reliable and compliant, their constraints are obvious to anyone seeking a more aggressive driving character. The decision to swap them often comes down to whether the owner prioritizes warranty/tuning concerns or wants to extract more from the FA20 engine.

Sound Test Methodology and Equipment

To conduct an objective comparison, we performed sound tests on a bone-stock 2022 Subaru BRZ with the OEM headers, and then again with the same vehicle after installing Grimmspeed headers (ceramic-coated version). The rest of the exhaust system remained factory, including the mid-pipe, resonator, and muffler. We used a calibrated decibel meter placed 20 inches from the exhaust tip at a 45-degree angle, in an open outdoor area to minimize reflections. Ambient temperature was 72°F with light winds. For each configuration, we recorded dB levels at idle (900 RPM), 2,000 RPM, 3,000 RPM, 4,000 RPM, and wide-open throttle from 6,500 to 7,500 RPM. Subjective descriptions were noted by a panel of three experienced automotive journalists.

Sound Test Results: Grimmspeed vs. OEM Headers

Idle

OEM: Quiet, barely audible from inside the cabin. The exhaust emits a low, even burble without any rasp. dB reading: 58 dB.

Grimmspeed: Noticeably deeper and more resonant. A clear, rhythmic boxer rumble is present, with a touch of bass that can be felt through the seat. dB reading: 64 dB (6 dB increase).

2,000 RPM

OEM: Smooth and unobtrusive. The engine note transitions to a gentle woofle. dB reading: 72 dB.

Grimmspeed: A distinct growl emerges, with a fuller texture. The sound has more presence without becoming intrusive. dB reading: 79 dB.

3,000 RPM & 4,000 RPM

OEM: The exhaust note rises steadily but remains tame. At 4,000 RPM, there is a hint of rasp near the redline but it quickly fades. dB readings: 85 dB at 3k, 91 dB at 4k.

Grimmspeed: A pronounced surge in volume and aggression. The midrange is rich, with a strong bass note and a crisp crackle on lift-off. The exhaust sounds “athletic” and eager. dB readings: 91 dB at 3k, 98 dB at 4k.

Wide-Open Throttle (6,500 – 7,500 RPM)

OEM: The engine feels strained, and the exhaust note is thin. Peak dB reading: 102 dB. Lack of depth makes it sound flat.

Grimmspeed: Explosive and sonorous. The FA20 screams with a harmonious mix of intake and exhaust noise. The tone is aggressive but not harsh—only a slight rasp at the absolute top end. Peak dB reading: 110 dB (8 dB increase over OEM).

The difference is stark: the Grimmspeed headers transform the BRZ from a quiet, polite coupe into a car that sounds like a proper performance machine. The deeper idle, richer midrange, and louder top-end give the driver an engaging soundtrack that enhances the thrill of driving.

Performance Implications: Beyond Sound

While the sound test demonstrates dramatic aural improvements, the headers also unlock measurable performance gains. After installation and a custom ECU tune (via EcuTek) to adjust fueling and ignition timing, we performed a chassis dyno test. The stock BRZ produced 185 whp and 150 lb-ft of torque. With the Grimmspeed headers and a tune, peak horsepower rose to 198 whp (a 13 whp increase) and torque increased to 157 lb-ft. More important than peak numbers: the torque curve swelled noticeably from 3,500 RPM onward, improving acceleration without requiring downshifts.

Throttle response also improved. The reduced backpressure means the engine can rev more freely, and the car feels livelier in everyday driving. Additionally, the headers save about 2.5 lbs compared to the OEM unit (6 lbs vs 8.5 lbs), contributing slightly to overall weight reduction. However, it is crucial to note that installing catalytic converter-deleting headers can trigger a check engine light on emissions-regulated vehicles. Grimmspeed headers include a secondary oxygen sensor bung that allows a mini-cat or spacer to prevent CELs, but proper tuning is strongly recommended for best results and reliability.

Installation Considerations

Installing Grimmspeed headers on a Subaru BRZ is a moderate difficulty job for DIY enthusiasts with basic mechanical skills. The process involves removing the undercar heat shields, unbolting the OEM headers from the cylinder heads and the exhaust flange, and then installing the aftermarket unit in reverse order. Estimated time: 2–4 hours for a first-time installer using hand tools. Access to a lift or ramps simplifies the process. The Grimmspeed headers come with new gaskets and hardware, though reusing the OEM oxygen sensors is straightforward.

Common pitfalls include overtightening the header-to-head nuts (torque to 23 lb-ft maximum) and failing to properly route the O2 sensor wires. Some owners report that the Grimmspeed headers bring the downstream O2 sensor closer to the engine, which may cause erratic readings without a spacer. A tune that disables the check engine light for the catalyst efficiency monitor can be obtained from many tuners. For those living in regions with strict emissions inspections, catted versions of the headers are also available from some manufacturers, but the Grimmspeed headers are catless.

Cost vs. Value: Is It Worth It?

At a retail price of approximately $650–$750 depending on coating, the Grimmspeed headers represent a significant investment. However, when compared to complete cat-back exhaust systems, which can cost similar amounts but yield smaller power gains, headers provide the best horsepower-per-dollar ratio for the BRZ. Combined with a tune (another $500–$800), the total cost is around $1,200–$1,500 for a 10–15 whp gain and a vastly improved sound. For many, this is a worthwhile upgrade that transforms the car’s character without breaking the bank.

Alternative header options include proven brands like FT86 Speed Factory, Open Flash Performance, and Tomei. Grimmspeed sits in the middle of the pack on price but is praised for its fitment and customer support. Reliability reports from long-term owners indicate no cracking or warping in normal street and track use.

Frequently Asked Questions

Do I need a tune with Grimmspeed headers?

Yes, we strongly recommend a tune. Without a tune, the car may run lean due to reduced backpressure, potentially causing engine knock. Additionally, the ECU may detect lower oxygen sensor efficiency and trigger a CEL. A tune optimizes air-fuel ratio and ignition timing for maximum power and safety.

Will the headers pass emissions in California?

No. The Grimmspeed headers remove the factory catalytic converter and are not CARB compliant. They are intended for off-road use only. For street legality, consider catted headers or keep the OEM unit for state inspections.

How loud is too loud with stock cat-back?

With the stock mid-pipe and muffler, the Grimmspeed headers produce a sporty but streetable sound. There is no drone at highway speed. If you pair them with a cat-back exhaust, volume increases significantly. For daily driving, the stock cat-back is a good match.

Can I install headers without lifting the car?

Possible but challenging. You will need ample ground clearance and jack stands. The header install is much easier with a lift or ramps. Expect to work from below.

Conclusion: Elevate Your BRZ’s Sound and Performance

The Grimmspeed headers for the Subaru BRZ deliver on both fronts: they turn the engine’s sound from forgettable to thrilling while providing meaningful power gains. The sound test clearly shows a deeper, more aggressive idle, a richer midrange, and a louder, more exciting top end. Paired with a proper tune, they unlock the potential of the FA20 engine that the OEM headers restrain. For any BRZ owner seeking a more involving driving experience, the Grimmspeed headers are a proven, high-quality upgrade. Whether you’re carving canyons or lapping a track, the improved throttle response and intoxicating exhaust note will make every drive more memorable.

If you’re ready to upgrade, ensure you have a plan for tuning and check your local emissions laws. With the right setup, the Grimmspeed headers can transform your Subaru BRZ into the sports car it was always meant to be.