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The HKS LEGAMAX Premium WRX STI/WRX 2015 US is designed for the 2015-2021 Subaru WRX. Match manufacturer part number 31021-BF001, the complete vehicle or system configuration, dimensions, connections, and included components before ordering.
Key Features
- Variable Pipe Diameter: 60.0mm to 80.0mm main piping expands to 115mm rolled edge tip for smooth high-flow exhaust without backpressure.
- SUS304 Stainless Steel Construction: Full system built from durable 304-grade stainless steel resists corrosion and ensures long-term performance under high heat.
- Weight Reduction: 15.2kg system weighs 21% less than stock 19.0kg setup improving handling and acceleration.
- Bolt-On Fitment: Direct replacement uses factory hangers and mounts for straightforward installation on STI models.
- Full SUS304 stainless steel piping muffler and 115mm single-layer tip for heat resistance and shine.
- Large Volume Chamber Muffler: Internal chamber design quiets drone while amplifying low-end torque and mid-range power.
Fitment
| Years | Make | Model | Application |
|---|---|---|---|
| 2015-2021 | Subaru | WRX | Confirm engine, body style, system configuration, and exact interface |
Specifications
| Brand | HKS |
|---|---|
| Manufacturer Part Number | 31021-BF001 |
| Product Type | Catback |
| Fitment Type | Vehicle Specific |
| Condition | New |
What's Included
One new HKS catback identified by manufacturer part number 31021-BF001, in the quantity stated by the title. Additional wiring, pipes, hoses, clamps, fittings, gaskets, fluids, tuning, tools, and installation hardware are included only when expressly listed for this exact part number.
About HKS
HKS develops exhaust, forced-induction, cooling, engine, electronics, and exterior components for import and performance vehicle applications.
Related HKS Products
- Shop all HKS products
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Frequently Asked Questions
How do I confirm this HKS exhaust part fits?
Match the manufacturer part number, listed year, make, and model, body style, engine, exhaust diameter, flange locations, and available underbody clearance.
Does this listing include every part needed for installation?
Only the items stated in the title and What’s Included section are supplied. Gaskets, adapters, hardware, hangers, or connecting pipes may be separate for some applications.
Will the exhaust change sound or require tuning?
Sound varies with the complete exhaust system and vehicle. Tuning requirements depend on the application, emissions equipment, and other modifications, so confirm with the vehicle tuner before installation.
Installation Instructions
Follow the current HKS instructions and the vehicle service manual for part number 31021-BF001. Compare every component, connection, dimension, and mounting point before disassembly. Use the correct tools, fasteners, torque values, fluids, wiring protection, and safety procedures, then inspect for leaks, interference, heat exposure, clearance, and secure operation before normal use.
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