Upgrading Your S2000 with Apex'i Power Headers

The Honda S2000 has earned its place as a modern classic, revered for its free-revving F20C or F22C engine and razor-sharp chassis. Enthusiasts know that unlocking the car's true potential often begins with improving airflow — and few modifications deliver a more dramatic transformation than a quality set of exhaust headers. Among the most respected options on the market are Apex'i Power Headers, which strike a careful balance between aggressive sound, increased torque, and reliable performance. Whether you are building a weekend track car or simply want more thrill from your daily drive, these headers offer a compelling upgrade.

Why Exhaust Headers Matter for the S2000

The factory exhaust manifold on the S2000 is a cast-iron piece designed to meet noise and emissions regulations, not to maximize power. It tends to restrict exhaust flow, especially in the mid-to-high RPM range where the S2000 truly shines. By replacing the restrictive manifold with a set of properly designed headers, you allow exhaust gases to exit the cylinders more efficiently. This reduces backpressure, lowers exhaust gas temperatures, and helps the engine produce more power with less pumping loss. Apex'i Power Headers are engineered specifically for the S2000's VTEC engines, ensuring optimal tube length and diameter for a broad torque curve and a signature exhaust note.

The Apex'i Advantage: Build Quality and Engineering

Apex'i has been a trusted name in Japanese performance parts for decades, known for precision-crafted exhaust systems and intake components. Their Power Headers for the S2000 are constructed from 304 stainless steel with mandrel-bent tubing to maintain smooth internal surfaces and consistent wall thickness. The flanges are laser-cut and CNC-machined for a perfect seal against the cylinder head, preventing exhaust leaks that can rob power and cause annoying ticking sounds. Each header is TIG-welded by skilled technicians, resulting in a durable assembly that can withstand the thermal cycles of track use or spirited street driving. This level of construction gives owners confidence that the headers will last as long as the car itself.

Key Benefits of Apex'i Power Headers

Increased Torque and Power

The most immediate benefit after installation is a noticeable gain in torque across the RPM range. While peak horsepower often gets the headlines, S2000 drivers will appreciate the extra shove from 4,000 to 6,000 RPM, making the car feel more responsive on back roads or during canyon carving. The precise tube sizing in Apex'i headers improves exhaust scavenging, which helps fill each cylinder with a denser air-fuel mixture. Many owners report gains of 8–12 horsepower and 6–8 lb-ft of torque at the wheels, with much of the improvement concentrated in the middle of the rev band. These figures hold up well even when combined with other bolt-on modifications like a cold-air intake or cat-back exhaust.

Aggressive Exhaust Tone

The S2000 already has a distinctive engine note, but the factory manifold muffles some of the higher-frequency harmonics. Apex'i Power Headers free up that sound, producing a deeper, more aggressive exhaust tone that intensifies as the tachometer sweeps toward redline. The change is particularly satisfying during full-throttle acceleration, where the exhaust note gains a raw, metallic edge without becoming obnoxious or droney at cruising speeds. For those who enjoy the aural experience of a naturally aspirated engine, this transformation alone makes the upgrade worthwhile.

Durability and Heat Management

High-performance driving generates extreme heat in the engine bay. Apex'i headers are built from stainless steel, which offers excellent thermal fatigue resistance compared to mild steel or cast-iron alternatives. The smooth mandrel bends also reduce hotspots where cracking could occur. Some versions come with an optional ceramic coating or feature a polished finish that helps reflect radiant heat away from sensitive components like the starter motor, alternator, and intake plumbing. Proper heat management not only prolongs header life but also maintains consistent intake air temperatures, supporting reliable power delivery even during extended track sessions.

Installation Overview: What to Expect

Fitting Apex'i Power Headers is a moderately involved job that most experienced DIYers can complete in a weekend. Below is a step-by-step outline, but always refer to the product-specific instructions for your S2000 model year.

Tools and Preparation

  • Socket set (metric, 10mm to 19mm), wrenches, extensions, and a swivel socket for tight spaces.
  • Jack stands and a floor jack, or a vehicle lift.
  • Penetrating oil (WD-40 or PB Blaster) for stubborn bolts, especially on older cars.
  • New exhaust gaskets (often included with Apex'i headers, but confirm beforehand).
  • Oxygen sensor socket and possibly a wire harness extender if the factory O2 sensor wiring is short.
  • Protective gloves and eye wear — exhaust parts get sharp and hot.

Removing the Stock Manifold

Start by disconnecting the negative battery terminal. Jack up the front of the car and secure it on jack stands. Remove the under-tray if equipped. You'll need to unbolt the front pipe from the catalytic converter or test pipe, then disconnect the oxygen sensors carefully to avoid damaging the wiring. The stock manifold is held by several bolts along the cylinder head flange; these are often tight and may require a breaker bar. Work methodically, loosening all bolts before removing the manifold. On older S2000s, heat cycling can make these bolts stubborn — penetrating oil applied the day before helps significantly.

Installing the Apex'i Headers

Before fitting the new headers, compare them to the stock manifold to confirm alignment. Install the supplied gaskets on the cylinder head studs. Position the Apex'i header against the head, and hand-tighten all mounting nuts evenly. Torque them in a crisscross pattern to manufacturer specifications (typically 18–22 ft-lbs). Reconnect the front pipe using the provided gaskets and hardware, ensuring a leak-free seal. Reinstall the oxygen sensors, using anti-seize compound on the threads. Some installations require bending the O2 sensor wire brackets slightly to avoid contact with the header tubes — check clearance thoroughly before lowering the car.

Post-Installation Checks

After everything is bolted up, start the engine and let it idle. Listen for exhaust leaks — a common sign is a ticking sound that changes with engine speed. You can use a soapy water spray on the flanges to spot bubbles. Once confirmed leak-free, take the car for a short test drive, paying attention to any unusual vibrations or contact between the headers and the chassis or steering shaft. Retighten all bolts after the first heat cycle, as thermal expansion can cause nuts to loosen slightly.

Performance Gains in Detail

Dyno-Proven Results

Independent dyno testing of Apex'i Power Headers on a bone-stock S2000 typically shows gains of 8–12 whp at peak and a noticeable bump in mid-range torque. When combined with a free-flowing cat-back exhaust and an ECU tune, total gains can exceed 20 whp — a significant increase for a naturally aspirated 2.0-liter engine. The torque curve becomes flatter and extends further into the higher RPMs, making the car feel stronger from corner exit to redline. These gains are achieved without sacrificing idling quality or low-RPM drivability, which is a strong testament to the engineering of these headers.

The Need for a Tune

While Apex'i Power Headers can be installed on an otherwise stock S2000 with no immediate issues, the engine's ECU may not fully adapt to the improved exhaust flow. To realize the full potential of the headers, a professional dyno tune or a reflash of the ECU using a platform like Hondata FlashPro is highly recommended. A proper tune adjusts air-fuel ratios and ignition timing to match the new exhaust dynamics, extracting maximum horsepower while maintaining safe operation. Many tuners report that a header-equipped S2000 responds more aggressively to timing changes, rewarding the owner with additional gains beyond just the hardware upgrade.

Choosing the Right Header Design

Apex'i offers two primary designs for the S2000: the 4-2-1 (tri-Y) configuration and the 4-1 (racing) configuration. Each has distinct characteristics suited to different driving styles and performance goals.

4-2-1 (Tri-Y) Headers

The 4-2-1 design groups the primary tubes from cylinders 1&4 and 2&3 into two secondary tubes before merging into a single collector. This arrangement creates two pressure pulses that improve mid-range torque and broaden the power band. For street-driven S2000s, the 4-2-1 is often the better choice because it provides stronger throttle response in the 4,000–7,000 RPM range where daily driving occurs. The sound is slightly more refined than the 4-1, though still much more aggressive than stock.

4-1 (Racing) Headers

By merging all four primary tubes directly into a single collector, the 4-1 design prioritizes top-end horsepower at the expense of some mid-range torque. This configuration is favored by track enthusiasts who spend most of their time above 7,000 RPM. The 4-1 headers produce a more intense, high-pitched exhaust note that cuts through the noise at the track. For a car that primarily sees street use with occasional track days, the 4-1 may feel a little flat below 5,000 RPM unless paired with a tune and other intake/exhaust mods.

Material and Coating Options

Apex'i headers are primarily available in polished stainless steel. Some special editions feature a ceramic coating, which reduces under-hood temperatures and gives a satin black or silver appearance. Ceramic-coated headers are more expensive but offer better heat retention inside the tubes (improving exhaust velocity) and protect against corrosion in wet climates. For most owners, the standard stainless steel version provides an excellent balance of performance and value.

Compatibility with Other Modifications

Apex'i Power Headers are designed to bolt directly to the S2000's factory exhaust system, but they pair exceptionally well with aftermarket cat-back exhausts and high-flow catalytic converters or test pipes. When upgrading headers, consider the rest of the exhaust path: a bottleneck in the mid-pipe or muffler can negate some of the gains. Many enthusiasts build a complete system using Apex'i headers with a compatible Apex'i cat-back or similar premium exhaust (e.g., GReddy, HKS, or Invidia). Additionally, a cold-air intake (such as the Apex'i Power Intake or a K&N kit) helps the engine inhale as freely as it exhales, maximizing the benefit of the headers.

Maintenance and Long-Term Care

Stainless steel exhaust headers are low-maintenance, but a few simple practices extend their life. After driving in wet or salty conditions, a wash and rinse of the underside can prevent cosmetic surface rust from developing on welds. High-performance header wrap is not recommended for Apex'i headers because it can trap moisture and accelerate corrosion at the tube bends; instead, rely on natural convection or ceramic coatings for heat management. Periodically check the header flange bolts for tightness, especially after the first few heat cycles. If you notice any signs of cracking or discoloration indicating overheating, have a professional inspect the weld integrity.

Conclusion: Why Apex'i Power Headers Are a Top Choice

For S2000 owners seeking a genuine performance upgrade that transforms both sound and driving feel, Apex'i Power Headers deliver on every front. They offer measurable torque gains, a thrilling exhaust note, and durable construction that withstands hard use. Whether you choose the 4-2-1 for street versatility or the 4-1 for track-oriented power, you are investing in a component that enhances the core character of the S2000 — its high-revving, naturally aspirated engine. Installation requires some mechanical ability, but the rewards are immediate and lasting. Pair these headers with a good tune and complementary exhaust parts, and your S2000 will feel like a completely different machine, eager to dance through corners and sing all the way to 9,000 RPM.

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