AMS Intake Manifold - Standard or Reversed (Subaru EJ)

Here it is! Introducing the AMS Performance Subaru EJ WRX/STI Intake Manifold. The manifold was designed with performance and big HP custom setups in mind. With the level of builds this manifold will be used in, there will be some customizing required. Get yours today!



AMS and its sister brand Alpha Performance have been at the top of the game for 15 years. From turn-key packages to individual components we can meet and exceed all kinds of performance goals. From drag racing to road racing to spirited driving on the streets, let AMS enhance your driving experience!

Stay Ahead Of Your Competition With The AMS Subaru EJ Intake Manifold!

The AMS Subaru Intake Manifold was designed to outperform the competition. We referenced many modern design examples and engineering studies to bring you the best intake manifold available for the Subaru EJ20 and EJ25 WRX & STI. After extensive testing we ended up with a manifold that makes more power than anything else currently available on the market!

Engineered To Be The Best

For the Subaru EJ Intake Manifold the plan was simple, take our years of engineering experience and design the best intake manifold available. Designed, prototyped, and tested in house by our team of Engineers, the AMS Subaru EJ Intake Manifold was created to be the best unit available on the market. By casting this manifold it is not only stronger, but it allowed us to optimize the power output by giving us the freedom to sculpt the interior geometry for maximum efficiency and airflow.

By utilizing Solidworks© & CFD (computational fluid dynamics) we started with an extremely large plenum size of 4.5L for the ultimate top-end power. We also designed CNC machined bellhorns which act as internal velocity stacks and allow for a broad power curve and high RPM horsepower capabilities. This allowed us to optimize massive 2.5" tapered runners and matched cylinder port angles to minimize turbulence and maximize power output. This was only achievable with the incorporation of the TGV section of the manifold. This allowed the taper to happen over the entire 13" length of the runners instead of it happening in only a few inches through the factory style TGV housing.

With the incorporation of the TGV housings into our manifold, we have made the AMS Subaru EJ Intake Manifold a cost-effective one piece solution. Gone are the days of having to purchase both an intake manifold, and separate TGV delete housings.

Unmatched Power Gains and Excellent Response

This AMS Subaru EJ Intake Manifold offers more than just top end power. This manifold gives you an amazingly wide power-band with a huge jump in power whenever you are in boost. This equates to greatly improved lap times on the road course and the confidence to leave any opponent in your dust when on the street or drag strip!

Be the guy to beat, order your AMS Subaru EJ Intake Manifold today!


  • 4.5 Liter Plenum Volume
  • 13" Equal Length Intake Runners (Measured from Face of Bellhorn to End of Runner)
  • 2.5" (63.5mm) Intake Runner Diameter (ID of Bellhorn)
  • Bellhorn OD 3.8" (96.7mm)
  • TGV Housing Replaced with Long Runner Design
  • Increased Port Size at Cylinder Heads Allow Matching to Larger Hand Ported or CNC
  • rted Cylinder Heads
  • Available in Standard or Reversed Configuration
  • Throttle Body Opening Accepts Larger Throttle Bodies up to 2.625 (66.675mm) or
  • 70mm with mild porting.

Product Notes

  • Some port matching may be required when used in conjunction with CNC or hand ported
  • cylinder heads.
  • The intake manifold is available with a standard or optional reverse throttle body
  • orientation, allowing for more direct intercooler pipe routing.
  • Larger throttle bodies can be used with proper modifications (Up to 70mm with minor
  • porting) (Larger throttle bodies may also require adapter flanges)
  • The intake manifold is flanged for 04+ STI drive by wire throttle bodies, but cable
  • throttle bodies can be used with custom fitting and flange adapter.
  • Standard configuration intercooler piping will need mild custom fabrication due to
  • placement of throttle body.
  • Reversed configuration requires the relocation of the alternator and removal of the A/C
  • compressor. Installation is not a direct bolt on and will require custom intercooler piping.
  • The intake manifold is designed to use a common Subaru aftermarket top feed injector
  • size. (48mm overall length / 11mm inlet - standard Subaru rail size / 14mm outlet) We
  • recommend the use of Injector Dynamics brand injectors.
  • Standard Subaru style injectors cannot be used. (Side Feeds, Stock STI Style Injectors)
  • Not compatible with stock fuel rails or lines.
  • Not compatible with top mount intercoolers.
  • Not compatible with hard pipe stock location turbo inlets, requires silicone inlets.
  • Not directly compatible with mounting the factory upper coolant reservoir.
AMS.31.08.0001-1 (Uncoated)
AMS.31.08.0001-2 (Red Powder Coat)
AMS.31.08.0002-1 (Uncoated)
AMS.31.08.0002-2 (Red Powder Coat)

warning_symbolWARNING: Operating, servicing and maintaining a passenger vehicle or off-road vehicle can expose you to chemicals including engine exhaust, carbon monoxide, phthalates, and lead, which are known to the State of California to cause cancer and birth defects or other reproductive harm. To minimize exposure, avoid breathing exhaust, do not idle the engine except as necessary, service your vehicle in a well-ventilated area and wear gloves or wash your hands frequently when servicing your vehicle. For more information go to

More Information
SKU AMS.31.08.000
Product Type Intake and Exhaust
Intake and Exhaust Induction, Intakes and Intercoolers
Brand AMS Performance
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