HKS 31019-AF023 Silent Hi-Power Cat-Back Exhaust System Stainless Steel - SUS304

The HKS Silent Hi-Power Exhaust System (31019-AF023) is a race-inspired cat-back exhaust engineered for enthusiasts who demand genuine performance gains without sacrificing daily drivability. Developed from HKS's extensive experience in endurance and GT racing in Japan, this system features an optimized offset muffler and piping layout designed to deliver maximum exhaust flow through the straightest possible path—minimizing unnecessary bends that restrict gas velocity and rob power.

What sets this apart from the standard Hi-Power line is the Silent Hi-Power "Silent Chamber" design—a closed-end inner silencer integrated directly into the muffler body. This chamber targets and absorbs low-frequency cabin drone that is often present during highway cruising, delivering a refined exhaust note that is aggressive under acceleration but composed at steady throttle. Because the Silent Chamber uses a closed-end design, only a minimal amount of exhaust gas enters it, ensuring no meaningful disruption to overall flow or power output.

Key Features:

• SUS304 stainless steel construction throughout muffler and tip assemblies for corrosion resistance and long-lasting high-luster finish
• 75mm (approximately 3-inch) main pipe diameter for reduced restriction and improved exhaust velocity
• 120mm tip outer diameter for an aggressive, motorsport-inspired appearance
• Silent Chamber inner silencer reduces low-frequency cabin noise without compromising exhaust flow
• Dual outlet (2-close) configuration for a clean, symmetrical tip layout
• Designed to fit stock rear underskirt — no bodywork modifications required
• Compatible with Spec-C models
• Improved mid-range boost response and high-RPM power for turbocharged applications
• Race-derived offset muffler and piping layout minimizes restrictive bends

Sound levels measure approximately 90 dB at wide-open throttle and 72 dB at idle (versus stock 82 dB and 67 dB respectively), delivering a sportier exhaust note while remaining well-mannered for street use. The HKS Silent Hi-Power is the ideal choice for performance enthusiasts seeking measurable power improvement paired with a refined, livable sound character.