How to Install the HKS GTIII-RS Turbo Kit on BRZ / 86

Bolting a turbocharger onto the FA20 flat-four is the single biggest power upgrade you can make to a 2013-2020 Subaru BRZ, Scion FR-S or Toyota 86, and the HKS GTIII-RS Turbo Pro Kit is the most complete way to do it. This install guide walks through the exact power numbers, the full parts list, a step-by-step overview, and the supporting modifications that keep a boosted FA20 alive. At our Tampa, FL shop we build these cars regularly, and the difference between a turbo BRZ that lasts and one that grenades comes down to the details below.

What Is the HKS GTIII-RS Turbo Pro Kit?

The HKS GTIII-RS Turbo Pro Kit is a complete bolt-on turbocharger system engineered specifically for the 2.0L FA20 engine in the Subaru BRZ, Scion FR-S and Toyota 86. Rather than piecing together a manifold, turbo and intercooler from different brands, the kit ships as a matched package designed around HKS's GTIII-RS turbine, which HKS calls the best turbo match for the 2.0L boxer. It replaces the restrictive factory unequal-length header with a purpose-built turbo manifold and adds a front-mount intercooler for consistent charge temperatures.

Inside the box you get the GTIII-RS turbocharger with wastegate actuator, a tubular exhaust manifold, a front-mounted intercooler with full charge piping, an air cleaner and suction pipe, turbo oil and water lines, a catless extension pipe, and all gaskets, brackets and hardware. Our variant is part number 11001-KT001, the catless-extension configuration intended for off-road and competition use.

How Much Power Does the HKS Turbo Kit Make?

On a stock FA20, the HKS GTIII-RS kit produces approximately 337 hp (342 PS) at 6,600 rpm and 288 lb-ft (391 Nm) of torque at 4,100 rpm at the crank. That transforms a car that leaves the factory with just 200-205 hp and 151 lb-ft — the naturally aspirated FA20's biggest weakness is a torque dip in the midrange, and boost erases it. Peak torque nearly doubles, and the flat-four finally pulls hard from 4,000 rpm to redline.

HKS rates the same GTIII-RS turbine at 454 PS (about 448 hp) on a built 2.1L stroker engine, so the kit has clear headroom for a future engine build. On stock internals, the kit runs roughly 12.3 psi (85 kPa) of boost. Because the FA20 uses a high 12.5:1 compression ratio, that boost demands quality fuel and a careful tune; most street cars run 7-10 psi on 91-93 octane pump gas and save the full 12-plus psi for E85.

Tools, Skills and Time You'll Need

This is an advanced installation and one of the more involved bolt-on jobs on the platform. A professional shop typically budgets 15-25 hours, and a well-equipped DIYer should plan on a full weekend or two. You will remove the factory exhaust manifold, drop the front bumper to fit the intercooler, and tap the engine's oil and coolant systems for the turbo feed and return lines.

At minimum you need a full metric socket and wrench set, a torque wrench, a floor jack and stands, an oil-line flare/AN wrench set, coolant and oil for the refill, thread sealant, and a laptop or handheld for flashing the tune. A lift and an air-tool set make the job dramatically faster. If you have never removed a header or plumbed oil lines, this is a job for an experienced technician — a missed oil-return line or a boost leak can end an engine.

Step-by-Step Installation Overview

The sequence below is a high-level roadmap. Always follow the printed HKS instructions and your tuner's guidance for torque specs and fluid capacities.

1. Prep and safety

Disconnect the battery, let the engine cool completely, then drain the coolant and engine oil. Raise the car on a lift or stands and remove the front undertray for access to the manifold and oil pan area.

2. Remove factory intake, header and front bumper

Pull the factory air box and intake, unbolt the equal-length or unequal-length header and downpipe, and remove the front bumper to make room for the front-mount intercooler and charge piping.

3. Mount the turbo manifold and GTIII-RS turbocharger

Install the HKS tubular exhaust manifold with fresh gaskets, then bolt the GTIII-RS turbocharger and wastegate actuator to the manifold. Torque everything to spec and confirm the turbo clocks correctly for the oil and coolant fittings.

4. Install the intercooler and charge piping

Mount the front-mount intercooler behind the bumper and route the supplied charge piping, securing every coupler and clamp. A single loose clamp is the most common cause of a post-install boost leak.

5. Plumb the oil and water lines

Connect the turbo oil feed and return lines and the coolant lines using the supplied fittings. The oil return must drain freely back to the pan — get this wrong and the turbo will smoke or fail.

6. Fit the catless extension and reconnect exhaust

Install the catless extension pipe to your existing cat-back or downpipe. Reinstall the air cleaner, suction pipe and front bumper.

7. Fit the supporting mods, refill and tune

With the car apart, this is the ideal time to install the fuel pump, clutch, oil cooler and catch can (below). Refill the coolant and oil, prime the system, and load your base or custom tune before the first start. Then leak-check, heat-cycle, retorque, and finish on a dyno.

Supporting Mods You Should Not Skip

A turbo kit is only as reliable as the parts feeding and holding it. Stock FA20 internals are generally safe to about 300 hp, and this kit lands above that, so the fuel system and clutch are mandatory upgrades, while the oil cooler and catch can protect the engine over the long term. Here are the four we install on every boosted BRZ, FR-S and 86 at NLP Performance.

DeatschWerks X2 Fuel Pump Module (DW300)

The factory fuel pump cannot feed a turbocharged FA20 at full load. The DeatschWerks X2 module drops in a 340 lph DW300 pump to supply the extra fuel the GTIII-RS demands, keeping air-fuel ratios safe as boost climbs. Running out of fuel is the fastest way to melt a piston, which is why this is the first supporting mod we install.

Exedy Stage 2 Cerametallic Clutch

The factory clutch slips almost immediately with 288 lb-ft on tap. Exedy's Stage 2 Cerametallic thick-disc clutch is engineered to hold the torque of a boosted FA20 while remaining street-drivable. A clutch that slips under boost wastes power and destroys itself, so pair the clutch with the kit from day one.

Mishimoto Thermostatic Oil Cooler Kit

Boost and track use push oil temperatures far beyond stock. Mishimoto's thermostatic kit adds a dedicated oil cooler that only opens once the oil is warm, so the engine still reaches operating temperature quickly in cold weather but never overheats under sustained load. Stable oil temperature is essential for a turbo FA20 that sees canyon runs or track days.

Radium Dual Catch Can Kit

The FA20's D-4S direct-injection system is prone to oil vapor coating the intake valves and, under boost, ingesting crankcase oil. Radium's dual catch can kit captures vapor from both the PCV and crankcase-vent sides before it reaches the intake, protecting valves and reducing the risk of pre-ignition. On a boosted D-4S engine, a quality catch can is cheap insurance.

Turbo Build Parts and Pricing at a Glance

HKS GTIII-RS Turbo Kit: Pros and Cons

The Bottom Line

The HKS GTIII-RS Turbo Pro Kit is the definitive forced-induction upgrade for the FA20 BRZ, FR-S and 86 — a matched, complete system that reliably makes around 337 hp on a stock engine when it is fueled, clutched and tuned correctly. Treat the fuel pump, clutch, oil cooler and catch can as part of the kit, not options, and load a professional tune before the first start. Do that, and you get a boosted flat-four that finally has the midrange torque the naturally aspirated car always wanted.