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HKS 31006-BF003 replaces the factory multi-outlet layout with a single right-side Hi-Power muffler. The straight-through design and large main pipe reduce restriction while creating a distinctly more aggressive exhaust character.
Key Features
- 74.7-to-85 mm center pipe diameter.
- Bullet-style muffler with a 119 mm outlet.
- Sliding tail-tip adjustment sets the outlet projection.
- Removable inner silencer provides a quieter configuration.
- SUS304 and coated SUH409 stainless-steel construction.
Specifications
| HKS USA application | 2015-2021 Subaru WRX STI sedan |
|---|---|
| Engine / chassis | EJ257 / VAF |
| Drivetrain | AWD |
| Main pipe | 74.7 to 85 mm |
| Outlet | 119 mm, single right-side |
Fitment
The verified HKS USA application is the 2015-2021 WRX STI 4-door. Do not substitute the newer VB FA24 exhaust. The kit manual includes two mid-pipe sections, the main muffler, gaskets and installation fasteners.
Installation & Included Components
Install using the HKS manual and check the complete system for clearance and leaks. The inner silencer changes noise level, not vehicle compatibility. Local noise rules still apply; track-style sound does not establish approval for every public-road jurisdiction.
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