AMS EJ25 Intake Manifold - Reverse Rotation - UNCOATED - 2002-2014 WRX, 2004-2021, 04-08 FXT

• Gains as high as 51 WHP seen in back to back dyno testing compared to OEM

• 4.5 Liter Plenum Volume for Massive Top End Power

• 13” Equal Length Intake Runners for a Perfectly Optimized Powerband

• Massive Airflow Supplied to the Engine via 2.5” (63.5mm) ID Intake Runners

• CNC Machined Billet Aluminum Bellhorns to act as Internal Velocity Stacks

• Increased Port Size at Cylinder Heads Allow Matching to Larger Hand Ported or CNC Ported Cylinder Heads

• Throttle Body Opening Accepts Larger Throttle Bodies up to 2.625” (66.675mm) or 70mm with mild porting

• Available with STI Red Powder Coating or Uncoated Configuration in either Standard or Reverse Throttle Body Orientation

Engineered To Be The Best

Unmatched power gains and excellent response

To validate the performance gains of the AMS Subaru EJ Intake Manifold, we conducted extensive back-to-back dyno testing across multiple vehicle setups. Each test was designed to isolate the manifold’s impact by comparing identical configurations with and without the AMS manifold installed. The results were clear: significant increases in power and throttle response across the board. On a 2007 STI equipped with an AMS Rotated Kit, PTE 6266, GSC S2 cams, ported heads, and Supertech +1mm valves running 93 octane, power jumped from 470 WHP to 521 WHP—a massive 51 WHP gain. Even on a more modest builds, like another 2007 STI setup with a GT30R turbo on pump gas saw power rise from 396 WHP to 410 WHP. Similarly, a 2008 STI with a PTE 5858 turbo gained 10 WHP, increasing from 398 to 408 WHP. These results confirm what we engineered this manifold to do: deliver broad, usable power gains throughout the RPM range. Whether you’re chasing lower lap times or faster quarter miles, the AMS EJ Intake Manifold gives you the boost in performance to pull ahead—where it matters most.

Product Notes

• General Manifold Fitment Information
  • Not compatible with top mount intercoolers.
  • Not directly compatible with mounting the factory upper coolant reservoir. Custom bracketry will need to be fabricated to mount.
  • 2008+ STI may require mild clearancing of A/C compressor line
  • Due to the large variety of rotated turbo kits on the market, we cannot guarantee fitment with every brand. Depending on the turbo location and sizing, interference with the cylinder 3 intake runner is possible.
  • Some port matching may be required when used in conjunction with CNC or hand ported cylinder heads.
  • The bottom of the center plenum features four 1/8″ and one 1/4″ NPT ports for vacuum accessories.
• Throttle Body and Intercooler Piping Information
  • Standard configuration intercooler piping will need mild custom fabrication due to placement of throttle body.
  • 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.
  • Larger throttle bodies can be used with proper modifications (Up to 70mm with minor porting) (Larger throttle bodies may also require adapter flanges)
• Reverse Orientation (Forward Facing Throttle Body) Information 
  • The intake manifold is available with a standard or optional reverse throttle body orientation, allowing for shorter and more direct intercooler pipe routing. at the front of the engine bay.
  • 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.
• Fuel Rail Fitment Information
  • Not compatible with side feed to top feed conversion rails due to different sidefeed rail mounting points (AMS manifold uses top feed rail mounting points)
  • Requires aftermarket rails and lines, will not fit with stock fuel rails and lines
• Injector Fitment Information
  •  We recommend the use of Injector Dynamics brand injectors, and cannot guarantee fitment of other manufacturer’s injectors. The AMS intake manifold is designed to use standard Injector Dynamics Bosch-style top feed injectors (part number ####.48.11.WRX.4). These Injector Dynamics injectors come with a lower cap preinstalled (WRX-16B) that must be removed before installation to allow for proper seating into the intake manifold injector port. (48mm body length, Rail side: 11mm bore red adapter, Manifold side: 14mm bore size )
  • The manifold is designed for top feed injectors and top feed fuel rails only. Side feed injectors, or conversion kits, will not fit.
  • OEM Subaru top feed injectors (including modified OEM injectors) will not fit and cannot be used.