GrimmSpeed 4-Piston Brake Caliper Kit (340mm Rotor) – Red – 2002-2021 Subaru WRX / STI

The Braking Upgrade the WRX/STI Factory Brakes Should Have Been

The GrimmSpeed 4-Piston Brake Caliper Kit with 340mmmm Rotor in Red for the 2002-2021 Subaru WRX / STI is a purpose-built, application-specific brake upgrade designed and tested for Subaru platforms — not a universal kit adapted to fit. Forged 6061-T6 aluminum caliper bodies, dual 44mm and 41mm pistons, Type 3 hard anodized heat-managed pistons, and a complete kit that includes everything needed for a fixed-caliper upgrade. This listing is the Red anodized finish — Gunmetal Gray also available.

Forged 6061-T6 Aluminum, Dual Piston, Heat-Managed Pistons

The GrimmSpeed caliper body is forged from 6061-T6 aluminum — a two-piece design, hard anodized for strength and corrosion resistance. The dual piston setup uses a 44mm primary and 41mm secondary piston to apply even pad pressure across the full pad face, reducing taper wear and maintaining consistent feel as the pads wear. Type 3 hard anodized, vented pistons manage heat buildup under sustained braking — a critical feature for track use where heat-soaked pistons lead to brake fade. At approximately 9.9 lbs per corner with bracket and hardware, the kit is meaningfully lighter than equivalent cast iron alternatives.

Complete Kit — Application-Specific Rotor and Bracket Included

Each GrimmSpeed kit is built for the specific Subaru application — the correct rotor size and mounting bracket are included, removing the sourcing complexity of fitting off-the-shelf big brake components. Compatible with factory brake lines on most applications, though new lines may be recommended depending on vehicle year and condition. Pad compatibility is FMSI D1001 or D968 depending on application — widely available pads that don’t require specialty sourcing.

Key Features

• Platform: 2002-2021 Subaru WRX / STI
• THIS LISTING: Red anodized finish — Gunmetal Gray also available
• Caliper body: forged 6061-T6 aluminum — 2-piece design, hard anodized
• 4-piston fixed caliper — 44mm primary / 41mm secondary pistons
• Type 3 hard anodized vented pistons — superior thermal management
• Rotor: 340mmmm — application-specific
• ~9.9 lbs per corner with bracket and hardware
• Pad compatibility: FMSI D1001 or D968 (varies by application)
• Compatible with factory brake lines on most applications
• Suitable for street and track use

Fitment Notes

• Platform: 2002-2021 Subaru WRX / STI
• Red anodized finish — Gunmetal Gray variant available separately
• Compatible with factory brake lines on most applications — new lines may be recommended
• Pad compatibility: FMSI D1001 or D968 — confirm by application
• Professional installation recommended

Straight From Subispeed

The GrimmSpeed 4-Piston Caliper Kit stands out because it was designed specifically for the Subaru platform rather than adapted from something else. The stock single-piston calipers on the WRX/STI work for street driving but fall short under sustained hard braking — heat soak causes fade and uneven piston pressure causes taper wear. The GrimmSpeed kit addresses those limitations at a price point well below a true Brembo upgrade, with application-specific fitment that removes the bracket and rotor sourcing headache.

What’s Included

• 2x GrimmSpeed 4-piston brake calipers — Red anodized
• 2x Vehicle-specific mounting brackets
• 2x 340mmmm brake rotors
• Hardware kit

About GrimmSpeed

GrimmSpeed is a Pacific Northwest-based performance parts manufacturer that has been building Subaru-specific hardware since 2003. Founded by engineers who were actively building and racing Subarus themselves, GrimmSpeed’s catalog reflects the priorities of people who use the products they make — turbo inlets, downpipes, uppipes, boost controllers, intercoolers, and engine bay accessories designed specifically for the EJ and FA-series Subaru platforms. Every GrimmSpeed product is engineered, tested, and refined in-house, and their focus on Subaru means the fitment and function reflect a deep understanding of the specific platforms they cover. Subispeed carries the full GrimmSpeed catalog because their approach to product development consistently produces parts that perform as advertised and fit correctly out of the box.

Year	Make	Model	Notes
2002-2021	Subaru	WRX	EJ205/EJ255/FA20DIT
2004-2021	Subaru	WRX STI	EJ207/EJ257