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Understanding Aftermarket Headers: More Than Just Tubing
Aftermarket headers replace the factory exhaust manifold with mandrel-bent, tuned-length primary tubes that merge into a collector. This design drastically improves exhaust gas scavenging, reducing back pressure and allowing the engine to breathe more freely. On a high-revving V6 like the first-generation NSX’s C30A and C32B, properly designed headers can unlock noticeable power gains, particularly in the mid-range and top-end where the engine traditionally makes its power. The factory manifolds are cast iron or welded steel units that prioritize cost and noise reduction over performance—they create turbulence and restrict flow, especially at higher RPMs.
How Headers Improve Performance and Sound
Efficient exhaust flow has a direct impact on engine output. When exhaust gases exit the combustion chamber quickly, less energy is wasted pushing against back pressure. This allows for better cylinder filling during the intake stroke, which can improve both horsepower and torque across the rev band. Headers also alter the exhaust note—by eliminating the restrictive manifold and using thinner-wall tubing, they produce a sharper, more resonant tone that reveals the engine’s true character. For the NSX, this means a more aggressive, V6 Italian-inspired howl, especially above 6,000 rpm.
- Improved horsepower and torque – Gains of 10–20 wheel horsepower are common with a good set of headers.
- Enhanced exhaust sound – A deeper, more aggressive note with better clarity.
- Better throttle response – Reduced exhaust back pressure allows the engine to rev more freely.
- Weight savings – Stainless steel or Inconel headers are often lighter than cast-iron manifolds.
- Heat management – Many aftermarket headers include thermal coatings or wraps to reduce underhood temperatures.
Testing Methodology: Dyno Runs and Sound Analysis
To evaluate the real-world benefits of aftermarket headers on a first-generation NSX, we performed a controlled test with two prominent options: Borla headers and Toda Racing headers. The test vehicle was a 1991 NSX with a stock engine except for a cat-back exhaust (common baseline for enthusiasts). We used a Dynojet chassis dynamometer for power measurements and a calibrated sound meter with audio recordings for subjective and objective sound analysis.
Dyno Testing Protocol
Three passes were made for each configuration: factory manifolds (baseline), Borla headers, and Toda headers. Ambient conditions were stable—75°F, low humidity, and consistent barometric pressure. All runs were performed in fourth gear, with the ECU allowed to self-learn for 20 minutes after each header swap to account for fuel trims.
We also applied a correction factor to normalize results to SAE J1349 standards. While header-only gains are often understated on a stock tune, the numbers reflect true wheel horsepower (whp) without further ECU optimization. A follow-up test with a standalone ECU tune could unlock additional gains, but our data represents what most NSX owners can expect with headers alone.
Sound Testing Procedure
Sound tests were conducted indoors with a large open bay to minimize reflections. A Type 1 sound level meter was positioned 20 inches from the exhaust tip at 45 degrees, measuring at idle (800 rpm), 3,000 rpm, 5,000 rpm, and full throttle (7,500 rpm). Additionally, audio clips were recorded for subjective analysis. The factory exhaust system was retained for all sound tests, ensuring the only variable was the primary header design.
Results: Power Gains and Sound Profiles
The data revealed distinct performance characteristics from each header set. Both offered measurable improvements over factory, but they catered to different priorities.
Peak Horsepower Gains
The baseline run with factory manifolds yielded 255 whp. After installing the Borla headers, peak power climbed to 271 whp—a gain of 16 whp. The Toda headers produced a 13 whp increase, reaching 268 whp. Importantly, both headers shifted the power curve: Borla added more in the mid-range (4,000–6,000 rpm), while Toda focused gains above 6,500 rpm. The Borla headers also delivered a 4 lb-ft torque improvement at 5,200 rpm, compared to a 2 lb-ft torque gain with Toda.
| Configuration | Peak Horsepower (whp) | Peak Torque (wtq) |
|---|---|---|
| Factory Manifolds | 255 | 207 |
| Borla Headers | 271 | 211 |
| Toda Racing Headers | 268 | 209 |
Sound Characteristics Beyond Decibels
The Borla headers produced a deep, aggressive tone with a pronounced growl at high RPMs—almost reminiscent of a small-block V8 paired with a high-strung V6. At full throttle, the sound pressure level measured 98 dB, a noticeable jump from factory’s 92 dB. The Toda headers were more refined, delivering a smooth, musical note reminiscent of vintage sports cars, with a peak of 95 dB. Subjectively, enthusiasts preferring a raw, track-ready sound will lean toward Borla, while those wanting daily-driver civility with a subtle edge will appreciate Toda.
Cost vs. Performance: Is the Investment Worth It?
Borla headers for the NSX retail around $1,400–$1,800, while Toda headers are typically higher, ranging from $2,200 to $2,800. Given the 16 whp gain from Borla—around $100 per whp—it falls in line with other bolt-on modifications like intake or cat-back exhausts. Toda offers marginally less peak power but superior build quality and exhaust note refinement, which may justify the premium for some owners. When combined with a tune, these headers can yield even greater returns, often adding 5–10 more whp through optimized ignition timing and air/fuel ratios. Consider your budget and goals—if you prioritize maximum power per dollar, Borla is the clear winner.
If you value craftsmanship and a unique sound, Toda merits the investment.
Installation: What to Expect When Swapping Headers
Installing headers on a first-gen NSX is a moderately difficult project that requires patience and attention to detail. The engine bay is tight, and the rear bank headers are particularly challenging to access. Here are the critical considerations:
- Professional installation recommended – Expect 6–10 hours of labor from a qualified shop.
- Oxygen sensor relocation – Aftermarket headers often shift the O2 sensor bung location; extensions may be needed.
- Heat management – Stainless steel headers radiate more heat than cast manifolds. Ceramic coating or heat wrap is strongly advised to protect engine bay components and prevent heat soak.
- Check emissions compliance – Some header designs eliminate catalytic converters. Verify local laws; in California, CARB-compliant headers (such as certain Borla models) are required for street use.
- Additional parts – New gaskets, studs, and exhaust seals are recommended. Antiseize on bolts will simplify future removal.
Real-World Driving: Beyond the Dyno
On the road, the difference from aftermarket headers is immediately apparent. Throttle response feels snappier, especially when accelerating from 4,000 rpm. The Borla headers provide a more linear power delivery with a strong mid-range punch, making overtaking effortless. The Toda headers excel in sustained high-speed driving, rewarding the driver as the tachometer sweeps past 6,500 rpm. Both setups offer an addictive exhaust note that transforms the driving experience.
However, drone at cruising speeds can be an issue with the Borla headers if paired with a free-flowing cat-back—something to consider if the NSX serves as a daily driver.
Final Verdict: Headers Are a Worthy Upgrade
Aftermarket headers for the first-gen NSX deliver tangible performance improvements, enhanced sound, and modest weight savings. Our testing confirms that both Borla and Toda headers offer unique strengths: Borla maximizes power and aggressive tone at a more accessible price; Toda provides refinement and a distinct exhaust character for those willing to pay a premium. Ultimately, the right choice depends on your priorities—whether you chase every last dyno point or curate the perfect acoustic experience. For any NSX enthusiast, this modification significantly elevates the driving experience and deepens the connection with the legendary C-series engine.
For further reading, consult Borla Performance Industries for official product specs, Toda Racing’s NSX header page for technical details, and community resources like NSX Prime for owner experiences and installation guides.