The Honda S2000 AP2, produced from 2004 to 2009, is revered among driving enthusiasts for its high-revving F22C1 engine, near-perfect weight distribution, and razor-sharp handling. While the car is already a joy on both road and track, many owners eventually seek more power and a sharper throttle response. One of the most complete and well-engineered solutions on the market is the HKS Power Pack. HKS—one of the most respected names in Japanese performance parts—has developed this kit specifically for the AP2 to deliver a balanced, reliable increase in output without sacrificing daily drivability. This guide covers everything you need to know about the HKS Power Pack for the S2000 AP2: the components, a detailed installation walkthrough, ECU tuning requirements, and realistic performance expectations.

What Is the HKS Power Pack?

The HKS Power Pack is a bolt-on performance package that combines an upgraded intake system, a free-flowing exhaust, and engine management tuning. Unlike piecing together parts from different manufacturers, the Power Pack is designed as a matched set, meaning the intake, exhaust, and ECU recalibration work together to produce optimal gains. For the Honda S2000 AP2, HKS has engineered the kit to complement the F22C1’s VTEC crossover and high-RPM powerband. According to HKS, the Power Pack can add approximately 20–25 wheel horsepower and a similar increase in torque, depending on the specific vehicle and fuel quality.

Components Included in the HKS Power Pack

Before diving into installation, it’s important to understand what comes in the box. The HKS Power Pack for the AP2 typically includes these four main pieces:

  • HKS Racing Suction Kit (intake) – A large, conical air filter mounted inside a heat-shielded enclosure, replacing the restrictive factory airbox. The intake piping is mandrel-bent for smooth airflow and is finished in HKS’s signature blue silicone couplers.
  • HKS Super Filter – A high-flow, washable foam filter element that offers excellent filtration while allowing more air into the engine. It is pre-oiled from the factory and can be cleaned with the HKS filter cleaner kit.
  • HKS Hi-Power Exhaust System – A cat-back exhaust made from polished stainless steel. It features a straight-through muffler design with a resonated tip to control noise while maximizing flow. The exhaust is designed to be a direct bolt-on replacement for the factory unit, retaining the stock catalytic converter for legality in most regions.
  • HKS F-CON iS or V Pro ECU Tuning – Depending on the specific kit version, HKS includes a piggyback ECU (F-CON iS) or a standalone unit (F-CON V Pro) with pre-loaded calibration maps. In some aftermarket bundles, a flash tune option via an HKS authorized dealer might be included. The ECU remap is the critical component that ensures the engine runs the correct air-fuel ratios and ignition timing for the increased airflow.

Note: Some retailers sell the Power Pack without the ECU, offering an “intake + exhaust” kit that requires a separate tune. Always verify what is included when purchasing. The full package with the HKS ECU provides the most cohesive solution.

Installation Guide: Step-by-Step

Installing the HKS Power Pack is a weekend-accessible project for anyone with moderate mechanical experience and a basic set of hand tools. You will need: a floor jack and jack stands, a set of metric sockets (10mm, 12mm, 14mm), a ratchet and extensions, screwdrivers, and possibly an O2 sensor socket if you plan to reuse the stock sensors. Allow 4–6 hours for a careful first-time installation.

1. Safety and Preparation

Park the vehicle on a level surface and ensure the engine is cool. Disconnect the negative battery terminal to prevent any electrical shorts. Jack up the front and rear of the car (as needed) and place securely on jack stands. You will be working underneath the car for the exhaust portion, so use proper supports.

2. Remove the Stock Intake System

Start by unclipping the intake resonator box from the front bumper area. On the AP2, you will need to remove the plastic shroud above the radiator grille and disconnect the rubber intake tube that runs from the airbox to the throttle body. Carefully unplug the mass airflow sensor (MAF) electrical connector. The MAF sensor itself is fragile—do not touch the wire filaments. Remove the factory airbox by releasing the metal clips and pulling it upward. Set aside the original hardware, as some of it may be reused.

3. Install the HKS Racing Suction Kit

Begin by mounting the HKS heat shield plate to the chassis using the supplied brackets. Position the large conical filter inside the shield, ensuring it sits level and does not contact any hot engine components. Attach the adapter pipe to the throttle body using the included silicone coupler and T-bolt clamps. Then slide the filter onto the pipe and tighten all clamps. Reconnect the MAF sensor (HKS provides a mounting boss or relocation kit for the sensor). Double-check that all connections are air-tight. A vacuum leak after the MAF will cause rough idle and potential damage.

4. Remove the Stock Exhaust

This step is best done with the car elevated. Locate the exhaust hangers: three rubber isolators along the cat-back section. Spray them with penetrating oil to ease removal. Unbolt the flange connecting the cat-back pipe to the catalytic converter (two 14mm bolts). Support the exhaust with a jack or a helper, then pull the rear hangers off the mounting studs using a pry bar or pliers. The stock exhaust can then be lowered. Note that the AP2’s muffler is fairly heavy—handle it carefully to avoid injury.

5. Install the HKS Hi-Power Exhaust System

The HKS exhaust is a direct bolt-on replacement. Slide the new system into the rubber hangers (they may be tight; use a small amount of dish soap as lubricant). Align the flange with the catalytic converter outlet and insert new gaskets if provided (or reuse the factory gasket if in good condition). Tighten the flange bolts to approximately 32–38 ft-lbs. Verify that the exhaust tip is centered in the bumper cutout. Some adjustment is possible by loosening the hanger clamps. Once aligned, fully tighten all hardware.

6. ECU Remapping

If you purchased the full HKS Power Pack with the F-CON iS or V Pro, follow the included wiring instructions to connect the piggyback unit in line with the main engine control unit. The F-CON iS typically plugs into the ECU harness without cutting wires. Secure the unit inside the cabin (commonly behind the glovebox) and route the harness through the firewall grommet. Load the pre-installed HKS mapping via the dedicated software (HKS F-CON Map Editor) using a laptop or consult a professional tuner. For kits that offer a flash tune (e.g., via HKS’s cooperation with EcuTek or a dealer), the process is simpler: connect a flash cable to the OBD-II port and upload the map. Always follow HKS’s specific instructions for your ECU version. Do not drive the car without the tune installed—the combination of a free-breathing intake and exhaust will cause the engine to run lean, risking detonation.

Performance Expectations and Real-World Results

After a correct installation and tune, owners can expect noticeable gains across the RPM range. Dyno results from various S2000 forums (such as S2ki.com) and HKS themselves show improvements of 20–25 whp and 15–20 lb-ft of torque at the wheels on a stock AP2. The peak power increase comes mostly in the mid-range and top end, with VTEC engagement feeling more aggressive. Throttle response improves dramatically because the intake and exhaust restrictions are removed. The sound becomes deeper and more aggressive, especially above 6,000 RPM, without being obnoxious for daily driving. The HKS Hi-Power muffler is known for a balanced tone—loud enough to be exciting but civilized during cruising.

It is important to set realistic expectations: the F22C1 is already high-strung, and naturally aspirated gains are limited. You will not gain 50 hp from this kit alone. However, the combination of intake, exhaust, and tuning creates a more responsive, stronger-feeling engine that pulls harder through the gears. For those seeking additional power, a high-flow catalytic converter or header could be added later, but the Power Pack is designed as a standalone upgrade.

What About Reliability and Emissions?

One of the strengths of the HKS Power Pack is that it is developed specifically for the AP2, with calibration maps created by HKS engineers. When properly installed and tuned, the engine should run within safe air-fuel ratios and ignition timing. The kit retains the stock catalytic converter, so it should pass emissions tests in most regions that do not require a visual inspection of intake modifications. The HKS Super Filter is reusable—cleaning every 10,000–15,000 miles will maintain performance. The exhaust system is made from 304 stainless steel and is corrosion-resistant. Many owners report zero issues even after years of use.

Comparing the HKS Power Pack to Other Options

Several companies offer performance packages for the S2000, including Toda Racing, Spoon Sports, and Mugen. The HKS Power Pack stands out for its balance of cost, performance, and completeness. Spoon and Mugen parts are often more expensive and may not include an ECU tune. Toda sells individual components but no bundled kit. The HKS package also benefits from the company’s strong tuning support and widespread availability. For DIY enthusiasts who prefer to choose each component separately, an alternative could be an AEM intake plus a GReddy exhaust paired with a FlashPro or K-Pro tune. However, the HKS Power Pack eliminates guesswork and the risk of mismatched parts.

Maintenance and Tips

  • Inspect the intake filter every oil change; clean and re-oil as needed to avoid restricting airflow.
  • Check all exhaust bolts and clamps after the first 500 miles of driving—they can loosen as the system expands and contracts.
  • Do not attempt to run the car with only the intake and exhaust installed without the tune. The stock ECU will not compensate properly, and lean conditions can damage the engine.
  • If you are not comfortable wiring an aftermarket ECU, have the installation performed by a reputable HKS dealer. Many will also dyno-tune the car for maximum safety and performance.
  • Consider upgrading the clutch if you plan to track the car frequently; the added torque may accelerate wear on a factory clutch with high mileage.

Conclusion

The HKS Power Pack is one of the most refined and effective bolt-on upgrades for the Honda S2000 AP2. It transforms the driving experience by unlocking the engine’s natural potential without introducing the headaches of custom fabrication or questionable tuning. The installation is straightforward for a competent enthusiast, and the results are reliable, predictable, and satisfying. Whether you use your S2000 as a weekend canyon carver, a daily driver, or an occasional track toy, the HKS Power Pack delivers a meaningful increase in performance while preserving the character that makes the AP2 special.

For more information and official product specifications, visit HKS Japan’s official website. For installation tips and owner feedback, the S2ki community forums are an invaluable resource. If you are considering a custom tune, consult a professional at a HKS-authorized dealer for the best results.