The Class KR (B71354R) is a JQR-certified rear section exhaust designed for two key generations of Subaru performance.

As a compliant replacement for the stock rear muffler, it delivers a deeper and more aggressive exhaust tone for both the EJ20-powered WRX STI and the FA20-equipped WRX S4, offering an accessible sound and styling upgrade that remains street-legal.

Product Highlights

🔰 DUAL-PLATFORM JQR CERTIFICATION
This rear section is officially JQR-certified (JQR20152009), confirming its performance, quality, and compliance for both listed vehicle types. It is engineered to meet Japan’s 2010 Acceleration Noise Regulation, ensuring a legal and verified upgrade for public road use.

🔊 MODEL-SPECIFIC SOUND ENHANCEMENT
Provides a tailored, sportier exhaust character for each compatible platform, measured within legal limits:

For WRX STI (EJ20):

• Nearby Exhaust Noise: 90 dB

• Idling Noise: 68 dB

For WRX S4 (FA20):

• Nearby Exhaust Noise: 88 dB

• Idling Noise: 63 dB

This ensures an appropriate and engaging auditory enhancement suited to each engine’s characteristics.

🔧 REAR PIECE-ONLY SIMPLE UPGRADE
A straightforward 2-piece “rear piece only” system. This configuration allows for a simple, direct bolt-on installation to replace the stock muffler, providing an immediate improvement in sound and the signature dual-exit slash-cut style.

🏗️ LIGHTWEIGHT DUAL-EXIT CONSTRUCTION
Crafted from high-quality stainless steel for lasting durability. The system achieves a noticeable weight saving over the original rear section:

• System Weight: 12.4 kg (OEM reference: 14.7 kg)

• Features a dual-wall style with dual slash-cut 96mm tailpipes for an aggressive rear presentation.

Technical Specifications & Application

This is a JQR-certified, street-legal stainless steel rear exhaust section for select Subaru WRX STI and WRX S4 models.

Key Details

• Product Name: Class KR Rear Piece Only [’10 Acceleration Noise Regulation Compliant Model]

• Product Code: B71354R

• JAN Code: 4512355209541

• Stock Status: In stock

Vehicle Compatibility
WRX STI (6MT)

• Chassis: CBA-VAB (Acceleration noise regulation applicable vehicle)

• Engine: 2.0L Turbo (EJ20)

• Drivetrain: 4WD (AWD)

• Grade: STI (including Type S)

• Transmission: 6MT

• Model Years: August 2014 – April 2020

• Note: Fitment for S207, S208, and TYPE RA-R models is not confirmed and is not JQR-certified.

WRX S4 (CVT)

• Chassis: DBA, 3BA-VAG (Acceleration noise regulation applicable vehicle)

• Engine: 2.0L Turbo (FA20)

• Drivetrain: 4WD (AWD)

• Grade: 2.0GT(-S) EyeSight, STI Sport EyeSight

• Transmission: CVT

• Model Years: August 2014 – March 2021

• Note: Cannot be installed on tS or STI Sport # models.

Construction & Dimensions

• Material: All Stainless Steel

• Pipe Diameter: 50×2 (Dual-pipe design)

• Tailpipe Diameter: 96 mm (Slash-cut style)

• Exit Direction: Dual, Left & Right

• Number of Sections: 2

• Unit Weight: 12.4 kg

• Packaging Size: 1200 × 300 × 350 mm

• Packaging Weight: 16.9 kg