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Reviewed by Kayton S.
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Process West Intake Manifold Street Version
Very high quality piece from Process West. Fast shipping to Hawaii! 🤙
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Product Fitment:
2004-2021 Subaru STI
The Process West Billet Intake Manifold range represents the pinnacle of design, engineering, and performance for Subaru WRX and STI platforms. Born from years of R&D, extensive testing, and countless prototype iterations, this manifold is the result of a no-compromise approach to performance and aesthetics.
Crafted for both street and race applications, the manifold is available in multiple configurations to suit a wide range of Subaru platforms—from MY99 GC8 to the latest WRX and STI models. The modular design allows compatibility with stock throttle bodies or 3” Hypertune billet throttle setups. Custom throttle flanges are also available on request.
Key Features:
Fully CNC-Billet Plenum & Bellmouths: Features a high-volume billet plenum and precision-machined bellmouths for optimal airflow and velocity.
High Boost-Ready Construction: Built using thick-wall, polished CNC mandrel-bent tubing and TIG-welded to withstand up to 100 PSI of boost.
Modular Design: Available for various Subaru generations and configurations, including stock or Hypertune throttle compatibility.
Optimized for Torque & Top-End Power: Runner length and plenum volume are engineered for strong low/mid-range torque while unlocking high-rpm performance.
Retains A/C Compatibility: Despite the large plenum, the Street version is fully compatible with factory air conditioning systems.
Tested Performance Gains: Expect ~9% power and torque gains on both stock and heavily modified engines—including those running E85.
Street or Race Options: The Street version offers aggressive performance with full drivability. For more high-rpm power, shorter billet TGVs (lower runners) can be supplied.
This intake manifold is not just a performance upgrade—it's a statement piece for serious Subaru builders. When only the best will do, the Process West Billet Intake Manifold delivers strength, flow, and performance that outclass every alternative on the market.
Very high quality piece from Process West. Fast shipping to Hawaii! 🤙
Not installed yet, but upon first inspection, some of the cleanest welds I've seen aftermarket.
Awesome product would be great if it came with fittings for the price that you pay for it. Also instructions and ideas on what to run with different on setups.
As soon as this item arrived, I could tell from the packaging itself, it was going to be a superb item. The welds are flawless. The manifold is quite a bit heavier than I expected. But really, its a big hunk of aluminum so of course it has some weight to it. The ports on the bottom of the manifold are a nice added feature to add peripheral MAP based devices. As this is not an american company, the threads for the ports are BSPT instead of NPT so a bit more effort to find fittings and it is a bit annoying to have to source them rather than include several fittings and plugs. I ordered 4 1/8" BPST fittings and 1 1/4" fitting. The 1/4" fitting thread in just fine but the 1/8" fittings (2 plugs and 2 barbs) do not thread very well so I am off to grainger or fastenal to see if I can get something that threads right in. I would rather not tap new threads on a brand new ~2000$ item. The plenum is huge and the runners have nice fittings inside the plenum that are rounded for improved airflow. Very nice.
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