Updated October 2026
The best clutch upgrade for a WRX or STI depends on the generation and power level: for a modified 2015 to 2021 WRX, the Clutch Masters FX350 is a strong street pick rated at 480 ft-lb of torque, and STI owners can choose the ACT Heavy Duty Performance Street Sprung kit or the Competition Clutch Stage 2 for street builds. High-power and track builds step up to ceramic puck or twin disc kits, such as the Clutch Masters FX400 or the Competition Clutch twin disc for the STI.
The stock clutch handles factory power well. As boost and torque increase, it starts to slip under hard acceleration and its limits show quickly. This guide covers clutch stages, the options that fit each generation, and how to choose the right clutch for your Subaru WRX or Subaru STI.
Best WRX and STI Clutch Upgrades at a Glance
| Model | Street build | High power or track |
|---|---|---|
| 2015 to 2021 WRX (FA20, 6-speed) | Clutch Masters FX350 | Clutch Masters FX400 6-puck |
| 2004 to 2021 STI (6-speed) | ACT HD Performance Street Sprung, Competition Clutch Stage 2 | Competition Clutch Stage 3, Stage 4, or twin disc, Clutch Masters FX400 8-puck |
| 2006 to 2014 WRX (5-speed) | ACT HD Performance Street Sprung kit | Competition Clutch Stage 3 with flywheel (2006 to 2011) |
| 2002 to 2005 WRX | Competition Clutch Stage 2 | Competition Clutch Stage 3 |
No clutch kits are listed here yet specifically for the 2022 and newer WRX, so ask the shop about current options for that generation.
Best Clutch for the 2015 to 2021 WRX
The Clutch Masters FX350 pairs a heavy-duty pressure plate with a sprung, full-face disc and is rated at 480 ft-lb of torque, roughly double the factory clutch’s holding capacity according to Clutch Masters. It is built for aggressively driven street cars and occasional track days, with firmer engagement than stock and some possible chatter. Like other Kevlar-style discs, it needs a 500 to 750 mile break-in.
Fitment depends on build date. Subaru changed clutch components partway through the 2018 model year, so 2015 to early 2018 cars use one FX350 kit and late 2018 and newer cars use another. Check your VIN with the shop before ordering.
For high-power FA20 builds, the Clutch Masters FX400 6-puck ceramic kit raises torque capacity further. Engagement is much more aggressive, so it suits track use and high-power builds more than daily driving.
Best Clutch for the STI
For street-driven STI builds, the ACT Heavy Duty Performance Street Sprung clutch kit with Monoloc raises clamping force with a sprung disc that absorbs driveline shock and keeps daily drivability intact. The kit includes ACT’s Monoloc flywheel, and it is listed for the STI through 2014, so confirm fitment for your year.
Competition Clutch covers the rest of the STI range for the 2004 to 2020 six-speed. The Stage 2 Steelback Brass Plus kit is a street-friendly step up, the Stage 3 segmented ceramic and Stage 4 six-pad ceramic kits handle more torque with more aggressive engagement, and the twin disc ceramic kit sits at the top for high-power and competition builds. Our Competition Clutch Stage 3 guide for the STI covers the segmented ceramic option in detail. Clutch Masters also offers an FX400 8-puck ceramic kit for the 2004 to 2021 STI.
Best Clutch for the 2006 to 2014 WRX
For the five-speed WRX, the ACT Heavy Duty Performance Street Sprung kit is a 240mm conversion that includes an ACT Streetlite flywheel, so no separate flywheel purchase is needed. ACT rates it at 449 ft-lb of torque. For 2006 to 2011 cars running more power, the Competition Clutch Stage 3 segmented ceramic kit also includes a steel flywheel.
Why Does the Stock Clutch Have a Ceiling?
The factory clutch is designed for comfort and longevity at stock power. Its clamping force is calibrated for the torque the engine makes from the factory. Once boost and torque climb, the stock clutch runs out of capacity. It slips under hard acceleration, engagement becomes inconsistent, and the smell of a hot clutch is usually the final sign it is time to upgrade. Our post on when it is time to upgrade your WRX clutch covers the specific signs to watch for.
What Do Clutch Stages Mean?
Clutch stages describe clamping force, friction material, and engagement feel. Because stage numbers are not standardized between brands, compare torque ratings and disc type rather than the stage number alone.
Stage 1 upgrades use a stronger pressure plate with an organic disc. Pedal feel stays close to stock, which suits mildly modified street cars. Stage 2 adds clamping force and a performance friction material, with a heavier pedal and slightly more aggressive engagement. This is the most common step for builds with an upgraded turbo or E85.
Stage 3 and above move to ceramic or puck-style discs. Engagement is aggressive and the pedal is heavier, which takes adjustment for daily driving. Twin disc setups split the load across two friction surfaces for the highest torque capacity and are aimed at high-power street, drag, and track builds.
What to Look for in a WRX or STI Clutch Upgrade
Match the clutch to the real power level. A ceramic clutch on a mildly modified street car is unnecessarily aggressive and makes daily driving unpleasant, while an organic street clutch on a high-power build will slip.
Daily driving versus track use changes the choice. Street builds benefit from sprung disc designs that absorb shock and keep engagement predictable. Track builds can run stiffer setups where torque capacity matters more than comfort.
Check what the kit includes. Some kits include a flywheel and others need a separate one, and some FA20 kits depend on build date. Break-in matters too, since performance discs need a proper break-in period to seat correctly and reach their rated holding capacity.
What to Pair With a Clutch Upgrade
A stronger clutch puts more load through the rest of the drivetrain. The built transmission guide for WRX and STI covers when the transmission becomes the limit on high-power builds. Upgraded engine mounts for WRX and STI keep the drivetrain stable under more torque, and the transmission mounts guide covers the other half of drivetrain movement.
Small supporting parts help the new clutch feel right. A clutch delay valve delete sharpens engagement, a billet clutch fork pivot removes slop from the factory pivot, the COBB six-speed shifter bushing for the STI tightens shift feel, and a lighter steel flywheel can sharpen throttle response on STI builds that keep the factory-style setup.
WRX and STI Clutch FAQ
What is the best clutch for a modified 2015 to 2021 WRX?
For aggressive street driving, the Clutch Masters FX350, rated at 480 ft-lb. High-power and track builds can step up to the Clutch Masters FX400 6-puck ceramic kit. The correct FX350 version depends on whether the car was built before or after Subaru’s mid-2018 clutch change.
What is the best clutch for an STI?
For street builds, the ACT Heavy Duty Performance Street Sprung kit or the Competition Clutch Stage 2. On high-power and track builds, the Competition Clutch Stage 3, Stage 4, or twin disc, or the Clutch Masters FX400 8-puck.
Is a ceramic clutch good for daily driving?
Usually not. Ceramic and puck-style discs grab hard and release quickly, which makes stop-and-go driving tiring. They suit high-power and track builds better than commuters.
Do I need a new flywheel with a clutch upgrade?
Sometimes. Some kits, like the ACT kits for the STI and the five-speed WRX and the Competition Clutch Stage 3 for the 2006 to 2011 WRX, include a flywheel. Others reuse the factory flywheel or need a separate one, so check the kit contents before ordering.
How long is the break-in for a performance clutch?
It varies by disc type. Clutch Masters calls for a 500 to 750 mile break-in on its Kevlar-style discs. Follow the manufacturer’s procedure, because skipping break-in shortens clutch life.
Will a performance clutch fit the 2022 and newer WRX?
Not every kit does. None of the kits in this guide are listed specifically for the 2022 and newer WRX, so confirm fitment with the shop before ordering.
Find the Right Clutch for Your WRX or STI
The right clutch comes down to the power level, how the car is driven, and how much engagement aggressiveness the driver is comfortable with on the street. Wrench Masters Auto sells these clutches and works on Subaru WRX and STI builds at its shop in St. Petersburg, Florida, so fitment and install questions can go straight to people who handle these cars every day. Browse the full range of clutch kits for WRX and STI, or read the OEM vs performance clutch guide to see what changes when you make the switch.
