SKU: 822615

Cobb Tuning Air/Oil Separator - Subaru WRX 01-14/STI 01-21





Note: Includes new PSR Bolt On RHD compatible mounting bracket and hardware.


RHD Mounting Bracket Notes:

  • Spacers are included to allow clearance of the surrounding fuel lines and wiring.
  • Supplied hoses/fittings from certain catch can/AOS kits may not be sufficient to install their product in this new location. Additional hoses/fittings may be required and sourced separately. For example, some cans may only include straight fittings where 90-degree fittings will work best.
  • For 01-07 Vehicles: Cable-Throttle Models with Cruise Control will need the PSR cruise control relocation bracket (sold separately).
  • For 08-14 WRX Vehicles: If fitted with Process West Verticooler a Kompact Turbosmart BOV (plumb back) will be required for clearance.
  • For 08-14 WRX and 08-21 STI Vehicles: Factory bracket for the engine wiring harness plug is removed but a new bracket is supplied with IAG AOS which can be bent and fitted with PSR bracket (see last photo above)

For more information on the PSR RHD Bracket click here


The COBB Air/Oil Separator is placed within your Subarus crankcase ventilation system and helps to prevent oil vapors from being introduced into the intake system. The COBB Air Oil Separator has been developed in partnership with IAG Performance and offers exclusive features.

  • 1 Liter Holding Capacity
  • Integrated ORB Ports
  • Compact Cast Aluminum Body w/ Black Powdercoat Finish
  • Heat Shielding on Crankcase Breather and Oil Return Lines
  • Coolant Bleeder Valve
  • Bespoke COBB Color Combination
  • Laser Etched COBB Logo

The Subaru EJ engine has 3 ports that vent crank pressure: one on each cylinder head and another on the top of the block. Each engine vent port receives its own connection to the AOS. By giving each engine port its own entrance to the AOS we have allowed for more effective and faster excavation of crankcase pressure. Additionally, this reduces overall system pressure. With a 4" OD and 5.75" height, the AOS has an approximate 1 liter of holding capacity. The larger the AOS, the more power you can safely make without having to worry about the AOS overfilling.

The bottom of the AOS is shaped like a snail, redirecting positive crank pressure into the same swirl pattern produced by the 3 side ports. Allowing maximum oil drainage while separating oil from the air in all the venting ports.

The back plate of the AOS features a unique coolant routing system that heats the entire AOS to the same temperature of the engine. This maximizes the evaporation of any water collecting inside of the can. The hotter the AOS, the less water will collect inside and mix with the oil.



The COBB Subaru Air/Oil Separator helps to prevent crankcase oil vapors from recirculating back through your engine's intake system.

Oil vapors passing through your engine's intake system lower the effective octane rating of fuel and can contribute to both oil and carbon buildup over time.



  • Compact Cast Aluminum Tank Design
  • Bespoke COBB Anodizing on Caps
  • Wrinkle Black Powder Coated Canister
  • Laser Etched COBB Logo
  • Developed in Partnership with IAG Performance


Vehicle Fitment:

  • 2001-2007 Subaru WRX (01-05 Cable Throttle Models require cruise control relocation bracket)
  • 2001-2007 Subaru STI (01-05 Cable Throttle Models require cruise control relocation bracket)
  • 2008-2014 Subaru WRX
  • 2008-2014 Subaru STI
  • 2015-2021 Subaru STI


SKU 822615
Brand Cobb Tuning
Shipping Weight 20.0000kg

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