HKS Hi-Power Cat Back Exhaust Single Exit Subaru WRX / STI 2015-2021 | 31006-BF003

The HKS Hi-Power Cat-Back Exhaust System is a premium performance upgrade engineered specifically for the 2015-2021 Subaru WRX and WRX STI. Designed and manufactured by HKS — one of Japan's most respected performance tuning brands — this single-exit muffler system delivers a refined, aggressive exhaust note while improving exhaust flow over the restrictive factory system. Whether you're building a track-ready STI or simply want a more exhilarating daily-driver WRX, the Hi-Power series strikes the ideal balance between performance gains and street-friendly sound levels. Key Features & Benefits Optimized Exhaust Flow — Mandrel-bent piping minimizes restriction and turbulence for improved scavenging and potential horsepower gains across the RPM range. Signature HKS Hi-Power Sound — Engineered muffler internals produce a deep, sporty exhaust tone that is aggressive under acceleration without being excessively loud at idle or cruising speeds. Premium Stainless Steel Construction — Built from high-grade stainless steel for superior corrosion resistance, long-term durability, and a polished appearance that holds up to daily driving and track use. Single-Exit Configuration — Clean, sleek single-exit tip design complements the WRX/STI rear bumper fascia for a purposeful, OEM-plus aesthetic. Direct Bolt-On Fitment — Precision-engineered to match factory mounting points and flanges for a straightforward, no-modification installation on compatible 2015 WRX and WRX STI models. Reduced Exhaust Back Pressure — Improved exhaust gas evacuation supports turbocharger efficiency, helping the EJ/FA powerplant breathe more freely under boost. HKS Quality Assurance — Every component is manufactured to exacting HKS standards and undergoes rigorous quality control, a brand with decades of proven motorsport heritage. What's Included HKS Hi-Power Cat-Back Muffler / Exhaust Section (Single Exit) Polished Stainless Steel Exhaust Tip OEM-Style Mounting Hardware & Gaskets Rubber Exhaust Hangers HKS Installation Instructions Specifications Manufacturer Part Number 31006-BF003 Brand HKS Series Hi-Power System Type Cat-Back Exhaust (Muffler Section) Exit Configuration Single Exit Material Stainless Steel Sound Level Sporty / Street-Oriented (Not Race Loud) UPC 4957266941485 SKU hks31006-BF003 Country of Origin Japan