AEM 21-863C Cold Air Intake for 2019-2021 Subaru WRX STI 2.5L

Vehicle Fitment

• 2019-2021 Subaru WRX STI (2.5L H4, VA / "VA-STI")

Features

• AEM DryFlow® synthetic, oil-free washable air filter
• Mandrel-bent aluminum intake tube for smooth airflow
• Custom heat shield to isolate intake from engine heat
• Conical filter design for high flow and engine sound enhancement
• Long service interval - up to ~100,000 miles between cleanings
• Easy bolt-on installation in about 90 minutes with basic tools
• AEM Lifetime Limited Warranty
• Designed to safely increase both horsepower and torque

Specifications

• Part Number: 21-863C
• Filter Type: DryFlow synthetic
• Tube Material: Aluminum
• Finish: Gunmetal Gray (or black variants depending on source)
• Replacement Filter: 21-2157DK
• Estimated Power Gain: ~16.5 HP (per some sellers)
• Weight: ~9.2 lb / ~4.2 kg (varies by source)
• Emissions: Not CARB-legal for use in California (per some listings)

Included Components

• 1x Aluminum intake tube
• 1x DryFlow® synthetic conical air filter
• 1x Heat shield
• Edge trim, brackets, and all mounting hardware
• Stainless-steel hose clamps

Product Description

The AEM 21-863C Cold Air Intake System is engineered specifically for the 2019-2021 Subaru WRX STI with the 2.5L H4 engine. It replaces the restrictive factory intake with a high-flow setup featuring a mandrel-bent aluminum tube and an oil-free DryFlow® synthetic filter to improve airflow, engine sound, and throttle response.

The system includes a custom heat shield to minimize heat soak, helping you draw in cooler, denser air for better performance. The conical DryFlow filter is designed for long service life - under normal highway use, it can go up to ~100,000 miles before needing cleaning.

Installation is straightforward and typically completed within 90 minutes using common hand tools. The AEM Lifetime Limited Warranty backs the part, making it a reliable upgrade for enthusiasts who want more power and sound without major modifications. Note: this part is not listed as CARB-legal, so check local emissions regulations before purchasing.