HKS GT2 Supercharger Review: 2000-2009 Honda S2000

The HKS GT2 supercharger is the gold-standard forced-induction kit for the Honda S2000 (AP1/AP2, 2000–2009). Honda's roadster is famous for a screaming 9,000-rpm redline and knife-edge handling, but its naturally aspirated F-series makes its ~240 horsepower up high — it is not a torque car. Boost fixes exactly that. In our Tampa, FL shop, the GT2 kit is the upgrade S2000 owners ask about by name, because it turns a peaky N/A four into a broad, tractable powerband that hits about 310 wheel horsepower without giving up daily-driver manners. This review breaks down the real power numbers, what is (and is not) in the box, the supporting mods you actually need, and how it compares to a turbo kit.

What Is the HKS GT2 Supercharger for the S2000?

The HKS GT2 S/C System Pro is a centrifugal supercharger kit designed specifically for the Honda S2000's F20C (2.0L, AP1) and F22C (2.2L, AP2) engines. Unlike a positive-displacement blower that sits on top of the intake manifold, a centrifugal supercharger spins a compressor wheel off the crank via a belt — making boost that climbs with rpm, which suits the S2000's high-revving character perfectly. Crucially, the GT2 kit ships intercooled: HKS includes an air-to-air intercooler and charge piping (with a relief valve) so intake temperatures stay in check on a boosted street car. It fits 2000–2009 AP1 and AP2 cars, with one important exception noted below.

This is a Pro kit, meaning it is the complete hardware package: supercharger unit, mounting and fitting hardware, oil-feed parts, pulley, belt, suction pipe, and the intercooler system. It does not include engine management or larger injectors — those are prepared separately, and we cover them below.

How Much Power Does the HKS GT2 Add?

The HKS GT2 supercharger makes about 310 wheel horsepower on the S2000 at roughly 10 psi of boost. Out of the box, HKS's published testing recorded 310.33 whp and 212.77 lb-ft at the wheels — a gain of roughly 70–90 whp over a stock AP1 (240 crank hp / ~205 whp) and a much fatter mid-range. The stock F20C and F22C both fall on their faces below 6,000 rpm; the centrifugal blower fills that hole, so the car pulls hard from 4,000 rpm all the way to its lofty redline. That broad, linear delivery — not just a bigger peak number — is why the GT2 has stayed the benchmark S2000 power adder for years.

What's in the Kit (and What HKS Leaves Out)

The GT2 Pro kit includes the supercharger unit, S/C oil-feed parts, all fitting and mounting hardware, the drive pulley and belt, the suction pipe, and the intercooler with its charge piping and relief valve. That is the entire boost-making hardware side of the equation. What HKS deliberately does not include are two things you must add:

• Engine management / control system. The GT2 kit does not ship with a tune or piggyback. You will need standalone or reflashed engine management (for example, a Hondata or AEM solution) and a dyno tune to run the blower safely.
• Larger fuel injectors. HKS states outright that the stock injectors cannot supply enough fuel for full supercharger output. A high-flow injector set is mandatory — we pair the GT2 with Grams Performance 1150cc injectors below.

One fitment note that trips people up: HKS lists the kit as unable to install on the AP2-110 (built 10/2007 and later) because of interference between kit parts and revised factory components. If your car is a late AP2, confirm the build date before ordering.

Supporting Mods: Fuel, Exhaust, Clutch & Monitoring

A supercharged S2000 is a system, not a single part. Beyond the mandatory 1150cc injectors and tune, we recommend three supporting upgrades so the car makes clean power and you can watch it happen. A free-flowing cat-back exhaust helps the blown F-series breathe on the way out, a boost gauge keeps you honest, and a stronger clutch handles the extra torque so you are not slipping the stock unit on hard pulls.

The Supercharged S2000 Build List

Here is the complete parts list we quote for a streetable, reliable ~310-whp S2000, in order of priority. The supercharger and injectors are non-negotiable; the exhaust, gauge, and clutch parts round out the build so it drives right and lasts.

Installing and Tuning the GT2 on Your S2000

Installation is a bolt-on job, but it is not a driveway afternoon. The GT2 is a belt-driven, self-contained unit that mounts to the front of the F-series and routes charge air through the included intercooler, so the job involves removing the intake tract, fitting the supercharger bracket, plumbing the intercooler piping, running the oil feed and return lines, and installing the larger injectors. In our Tampa shop we budget roughly a full day of labor for a clean, no-surprises install, plus dyno time. Do it once, do it right: the oil-feed plumbing and belt alignment are the two areas where rushed installs cause problems later.

Tuning is where the power — and the safety margin — actually comes from. Because HKS ships the kit without engine management, you will pair it with a reflash or standalone (Hondata and AEM are the common S2000 choices) and have it tuned on a dyno with wideband feedback. A good tuner dials in fuel and timing for the roughly 10 psi the base pulley makes, targeting safe air-fuel ratios under boost. This is not optional: the single most common cause of a hurt supercharged S2000 is running the stock injectors or a generic map. With the 1150cc injectors and a proper calibration, the F20C/F22C is a genuinely durable platform at this power level, which is a big part of why the GT2 has such a strong reliability reputation.

Why a Centrifugal Supercharger Suits the S2000

The S2000 was engineered around high rpm: the AP1's F20C makes peak power near 8,000 rpm and spins to a 9,000-rpm redline, while the AP2's larger-displacement F22C trades a little top-end for more low-end torque. A centrifugal supercharger is a natural match because its boost curve climbs with engine speed — it makes the most pressure exactly where the S2000 wants to live, high in the rev range, rather than dumping a wall of low-rpm torque that the chassis and clutch would struggle to use. That is why a GT2-equipped car still feels like an S2000, just with a mid-range that finally matches its top-end and a soundtrack of belt whine layered over that F-series wail. In our experience, owners coming from bolt-on N/A setups describe the change as transformative rather than merely a bigger number on a dyno sheet.

HKS GT2 Supercharger: Pros and Cons

HKS GT2 Supercharger vs Turbo Kits for the S2000

For a street-driven S2000 that you still want to daily, the HKS GT2 supercharger is easier to live with than most turbo kits. A centrifugal blower makes near-instant, linear boost with no lag, adds less underhood heat than a turbo manifold tucked against the firewall, and installs as a self-contained belt-driven unit. Turbo kits can make more peak power — 350 to 450-plus whp is on the table — but they cost more once you add a manifold, downpipe, wastegate, intercooler, and a bigger fuel system, and they typically bring more lag and heat. Our take: if your goal is roughly 300–320 whp with factory-like drivability, the GT2 is the better tool. If you are chasing a 400-whp track build and do not mind the extra complexity, look at a dedicated turbo kit. Either way, the S2000's F-series bottom end is generally happy at these power levels on a good tune.