The Class KR (B71364R) is a JQR-certified rear section exhaust designed for the Subaru WRX S4.

As a regulation-compliant replacement for the stock rear muffler, it delivers a deeper and more aggressive exhaust tone while maintaining street legality and offering a refined dual-exit aesthetic.

Product Highlights

🔰 JQR-CERTIFIED & STREET-LEGAL REAR SECTION
This rear piece is JQR-certified (JQR20222142), confirming its performance, quality, and compliance. Engineered to meet Japan’s 2010 Acceleration Noise Regulation, it is a direct, legal upgrade for the WRX S4’s exhaust note and appearance.

🔊 AGGRESSIVE YET COMPLIANT SOUND
Elevates the vehicle’s auditory character with a more pronounced and sporty tone, measured within strict legal limits:

• Nearby Exhaust Noise: 91 dB

• Idling Noise: 64 dB
  This provides a satisfyingly deep exhaust presence that enhances the driving experience without compromising daily comfort.

🔧 REAR PIECE-ONLY SIMPLE UPGRADE
A straightforward 2-piece “rear piece only” system designed for the CVT-equipped WRX S4. This configuration allows for an easy and direct bolt-on installation, providing an immediate upgrade in sound and style while retaining the factory center pipe.

🏗️ 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: 13.8 kg (OEM reference: 14.8 kg)

• Features a dual-wall style, with dual 96mm left-and-right tailpipes for an aggressive rear presentation.

Technical Specifications & Application

This is a JQR-certified, street-legal stainless steel rear exhaust section for the Subaru WRX S4.

Key Details

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

• Product Code: B71364R

• JAN Code: 4512355225374

• Stock Status: In stock

Vehicle Compatibility
WRX S4

• Chassis: 5BA-VBH (Acceleration noise regulation applicable vehicle)

• Engine: 2.4L Turbo (FA24)

• Drivetrain: 4WD (AWD)

• Grade: GT-H, STI Sports R (including EX trim)

• Transmission: CVT

• Model Years: From November 2021

Construction & Dimensions

• Material: All Stainless Steel

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

• Tailpipe Diameter: 96 mm

• Exit Direction: Dual, Left & Right

• Number of Sections: 2

• Unit Weight: 13.8 kg

• Packaging Size: 1200 × 400 × 450 mm