AMS Performance EJ20/EJ25 Intake Manifold

The AMS Performance Subaru Intake Manifold is engineered to deliver superior performance for Subaru EJ20 and EJ25 WRX & STI engines. It boasts a substantial 4.5-liter plenum volume and 13-inch equal-length intake runners with a 2.5-inch inner diameter, designed to maximize airflow and power output. This manifold replaces the factory TGV housing with an integrated long runner design, allowing for smoother airflow transitions and compatibility with larger, hand-ported or CNC-ported cylinder heads. The throttle body opening is designed to accept larger throttle bodies up to 70mm with minor modifications, and it features an optional reverse throttle body orientation for more direct intercooler pipe routing. Installation of the reversed configuration requires relocation of the alternator and removal of the A/C compressor, and will necessitate custom intercooler piping. Standard configuration intercooler piping will also require mild custom fabrication due to throttle body placement. This intake manifold is designed for common Subaru aftermarket top-feed injectors (48mm overall length, 11mm inlet, 14mm outlet) and is not compatible with standard Subaru side-feed or stock STI-style injectors, stock fuel rails or lines, or top-mount intercoolers. Furthermore, direct mounting of the factory upper coolant reservoir is not possible, and custom bracketry will be needed. The manifold includes four 1/8" and one 1/4" NPT ports on the bottom of the center plenum for vacuum accessories. Some port matching may be required for optimal performance with CNC or hand-ported cylinder heads. For 2008+ STI models, mild clearancing of the A/C compressor line may be necessary.