ACT ACTSB12-XTG6 Xtreme Race Sprung 6 Pad Clutch Kit 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 Subaru WRX Impreza WRX EJ255 FA20 FA24

The ACT ACTSB12-XTG6 is ACT's top-tier Xtreme race sprung 6-pad clutch kit, engineered for Subaru WRX, Impreza WRX, Forester XT, Legacy GT, and Outback XT applications running the 2.0L and 2.5L Turbo flat-four engines. This kit delivers a rated torque capacity of 681 ft-lbs at the crank, approximately 111% over OE, using ACT's 240mm Xtreme pressure plate paired with a 6-Pad Sprung Ceramic Race Disc and the ACT XACT Prolite Chromoly Flywheel. This is a 240mm conversion kit designed for high-power WRX and Impreza WRX builds where maximum clamp load and heat resistance are non-negotiable. It ships as a complete bolt-in assembly including flywheel, pressure plate, disc, release bearing, and alignment tool.

What's Included

• ACT Xtreme Pressure Plate (XT clamp load, 240mm)
• ACT 6-Pad Sprung Ceramic Race Clutch Disc (240mm / 9.4 in, spring-centered hub)
• ACT XACT Prolite Chromoly Flywheel #600895 (8.5 lbs, required for 240mm conversion)
• Release Bearing
• Alignment Tool

ACT Xtreme Pressure Plate

This kit is built around ACT's Xtreme (XT) pressure plate, which produces a higher clamp load than the Heavy Duty (HD) version used in kits like the ACTSB12-HDG6. Both plates share ACT's exclusive diaphragm spring design and four-stage heat treatment process, but the XT plate pushes clamp force significantly further to support the 681 ft-lbs torque rating needed by built EJ or FA-series engines making serious power.

ACT uses precision cover stampings that maintain consistent geometry under extreme heat cycling. The diaphragm is engineered to hold release travel consistent over the life of the disc, so pedal feel remains predictable even after thousands of aggressive shifts. For any WRX or Impreza WRX running more than a stage 2 tune, the XT pressure plate is the appropriate choice over a Heavy Duty plate.

6-Pad Sprung Ceramic Race Disc

The clutch disc in this kit measures 240mm (9.4 inches) in diameter, which is a conversion up from the stock 230mm used on most WRX and Impreza WRX applications through early 2018. The six ceramic puck layout maximizes surface contact under boost, with each pad bonded to a full-depth carrier plate. Ceramic compounds withstand sustained high temperatures that would glaze or destroy an organic disc in aggressive driving conditions.

The sprung (spring-centered) hub is a meaningful distinction from rigid-hub alternatives. The coil springs in the hub absorb driveline shock at engagement and suppress gear rattle at idle and light throttle. On a street-driven WRX or Impreza WRX, a sprung hub makes living with a race-grade disc substantially more tolerable compared to a rigid-hub ceramic setup. This kit uses a sprung hub; the companion ACTSB12-XTR6 uses a rigid hub and is oriented more strictly toward track-only applications.

ACT XACT Prolite Chromoly Flywheel

The kit includes ACT's XACT Prolite Chromoly Flywheel #600895, weighing just 8.5 lbs. This flywheel is not optional for this kit. Because the kit upgrades the clutch diameter from 230mm to 240mm, the XACT Prolite flywheel is required to match the mating surface geometry. Attempting to use the OEM flywheel with this disc will result in improper fitment.

The weight reduction from the OEM flywheel to the 8.5 lb Prolite flywheel is substantial. A lighter flywheel reduces rotational inertia, which translates directly to faster throttle response and quicker revving between shifts. On a turbocharged flat-four like the EJ255 or FA20, this improvement is immediately noticeable during hard acceleration and sequential up-shifts. Chromoly steel construction ensures the flywheel handles repeated heat cycling from sustained high-load driving without cracking or warping.

Vehicle Fitment

Fitment Notes

The ACTSB12-XTG6 is a 240mm conversion kit. The included ACT XACT Prolite Flywheel #600895 is required and cannot be substituted with the stock flywheel, as the stock flywheel does not match the 240mm disc mating surface. Most Subaru WRX and Impreza WRX models through early 2018 shipped with a 230mm OEM clutch, making this a genuine upsized conversion.

Note for 2018 WRX owners: Subaru introduced OEM 240mm clutch components partway through the 2018 model year. Vehicles with a VIN sequence after J806877 may already have OEM 240mm components. This does not affect compatibility with this kit, but buyers with a mid-production 2018 WRX should verify their existing clutch diameter before ordering to understand whether the flywheel swap is still necessary for their specific vehicle.

Full Specifications

California Prop 65 Warning

WARNING: This product can expose you to chemicals including lead, which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information, visit www.P65Warnings.ca.gov.

Warranty and Magnuson-Moss Act

This kit is covered by a 12-month ACT limited warranty from Advanced Clutch Technology against defects in materials and workmanship under normal use conditions. This warranty does not cover wear items or damage resulting from misuse, improper installation, or use in competition beyond the stated torque capacity.

Under the federal Magnuson-Moss Warranty Act, installing an aftermarket performance part does not automatically void your vehicle's factory warranty. A dealer must demonstrate that the aftermarket part caused a specific failure before denying a warranty claim on that component. Retaining all installation documentation and receipts is recommended. Consult a qualified attorney if a dealer attempts a blanket warranty denial related to this installation.

ACT SB12 Series Clutch Kit Comparison

All kits in the SB12 series are designed for the same Subaru WRX and Impreza WRX applications. They share the same flywheel and differ only in pressure plate clamp load, disc compound, and hub type. The table below makes it straightforward to select the right kit for your power level and driving style.

About Advanced Clutch Technology (ACT)

Advanced Clutch Technology has been manufacturing performance clutch systems in Lancaster, California since 1994. ACT designs and assembles its pressure plates, discs, and flywheels in the United States, maintaining direct control over component quality from raw material to finished kit. ACT supplies clutch systems to racing teams across multiple disciplines and to performance drivers who use their vehicles on the street and track. The engineering philosophy behind every ACT product is straightforward: build components that hold up to sustained abuse without asking the driver to compromise on streetability unless they choose to do so. The XTG6 is a product of that philosophy, developed specifically to handle the demands of built and turbocharged Subaru powertrains.

Frequently Asked Questions

Should I choose the ACTSB12-XTG6 (Xtreme) or the ACTSB12-HDG6 (Heavy Duty)?

Both kits use the same 6-pad sprung ceramic disc and the same XACT Prolite flywheel. The difference is the pressure plate. The ACTSB12-HDG6 uses the Heavy Duty plate rated at 574 ft-lbs; the ACTSB12-XTG6 uses the Xtreme plate rated at 681 ft-lbs. If your WRX or Impreza WRX is running a stage 2 tune with modest supporting mods, the HDG6 is sufficient. If you are running a built motor, large-frame turbo, or pushing beyond 400 wheel horsepower, the ACTSB12-XTG6 is the correct choice. The Xtreme plate also holds up better to high-frequency track use where the clutch sees sustained heat.

Does the ACTSB12-XTG6 fit the Subaru WRX STI?

No. The STI uses a different transmission, different bellhousing, and a larger OEM clutch than the WRX. This kit is engineered specifically for the WRX (FA20 and FA24) and the Impreza WRX (EJ255), along with compatible Forester XT, Legacy GT, and Outback XT applications. ACT produces dedicated STI kits under a separate part number series. Confirm your exact vehicle before ordering.

What is the difference between a sprung hub and a rigid hub clutch disc?

A sprung hub disc contains coil springs inside the hub that cushion the initial shock when the clutch engages. This reduces the driveline jolt at take-up, suppresses gear rattle at idle, and extends transmission and differential life compared to a rigid hub. A rigid hub disc is stiffer and more direct, which some track-only drivers prefer for the fastest possible power transfer. For any WRX that sees regular street use, the sprung hub in this kit is the better choice. ACT's rigid-hub equivalent is the ACTSB12-XTR6.

Why does this kit use a 240mm disc when my WRX has a 230mm OEM clutch?

ACT engineered the SB12 series around a 240mm diameter to increase the friction surface area, which contributes to both higher torque capacity and better heat dissipation. The larger diameter is not compatible with the OEM 230mm flywheel, which is why this kit includes the XACT Prolite flywheel as part of the assembly. The flywheel is a required component, not an optional upgrade. ACT sized the flywheel specifically for this disc, so the 240mm conversion is fully accounted for in the kit design.

What is the benefit of the 8.5 lb XACT Prolite flywheel over the stock flywheel?

The OEM WRX flywheel is substantially heavier. Reducing flywheel weight lowers rotational inertia, which means the engine can change RPM more quickly. In practice, this produces noticeably faster throttle blips, quicker rev-matching on downshifts, and more responsive acceleration out of corners. The chromoly steel construction of the Prolite flywheel ensures it handles repeated heat cycling without the cracking or distortion risk associated with lightweight aluminum flywheels under sustained track use.

Will 681 ft-lbs of torque capacity be enough for my build?

For context, a stock WRX produces roughly 258 ft-lbs of torque at the crank. Even an aggressively built EJ or FA-series engine with a large-frame turbo rarely exceeds 500 ft-lbs at the crank in street trim. The 681 ft-lbs rating provides substantial headroom for virtually any street or street-track build. If you are running a full competition build with sustained high-boost passes, consult ACT's technical support to confirm the application. For most performance WRX and Impreza WRX builds, the XTG6 is the ceiling of what the drivetrain can absorb before other components become the limiting factor.

What is the recommended break-in procedure for the ACTSB12-XTG6?

ACT recommends a break-in period of approximately 500 miles for ceramic disc kits. During this period, avoid slipping the clutch excessively, launching at high RPM, or sustained high-load driving that generates extreme heat before the disc surface has seated against the flywheel and pressure plate. Normal driving with clean engagements is the goal. After 500 miles, the disc surfaces will be properly bedded and the kit will perform at its rated capacity. Skipping break-in on a ceramic disc can reduce the service life of the disc and pressure plate surface.

How does pedal feel change after installing this clutch kit?

The Xtreme pressure plate produces noticeably higher pedal effort than a stock or Heavy Duty clutch. This is a direct result of the increased clamp load. Drivers coming from a stock WRX clutch will feel a stiffer pedal that requires more deliberate modulation. The engagement point of the ceramic disc is also more distinct and less gradual than an organic full-face disc, which means smooth launches require more attention until the driver adapts. In stop-and-go traffic, the higher pedal effort is a real consideration. Most performance drivers accept this trade-off given the torque capacity and longevity this kit provides under boost.

Does installing an aftermarket clutch void my Subaru factory warranty?

The federal Magnuson-Moss Warranty Act prohibits manufacturers and dealers from voiding a vehicle warranty solely because an aftermarket part was installed. A dealer must demonstrate a causal link between the aftermarket part and a specific failure. Installing this clutch kit does not automatically void coverage on unrelated systems. However, a dealer could argue that clutch-related drivetrain failures are caused by the aftermarket clutch. Keep all purchase receipts and installation records, and consult the Magnuson-Moss Act provisions or an attorney if you encounter a warranty dispute related to this installation.

Is the flywheel in this kit compatible with any other ACT disc or can I reuse it if I upgrade later?

The ACT XACT Prolite Flywheel #600895 included with this kit is designed for the 240mm disc format used across the SB12 series. If you later decide to change disc compounds or pad configurations within the SB12 family, the flywheel is reusable as long as it is in good condition and has not been overheated or warped. ACT recommends resurfacing the flywheel friction surface whenever a new disc is installed to ensure proper seating. A flywheel that has been cracked, heat-checked, or out-of-spec for runout must be replaced rather than reused.