The Process West range billet manifolds is a no holds barred manifestation of what is possible under the hood of a WRX/STI when perfect aesthetics meet high end performance. What you see here is the result of years of research and testing, multiple prototypes and a ground up fully featured design process that makes this a key asset of our product range. Available in two major configurations they feature a full billet plenum with generous billet bell mouths and thick wall polished CNC mandrel bent tube components. High end TIG welding assembly makes them suitable for up to 100psi boosted applications. No other product comes close to this level of strength and detail. The range is modular to suit everything from MY99 GC8 to the latest WRX and STI's with any stock throttle or that to suit the 3" Hypertune billet throttle. Custom throttle flanges are available on special request.

The plenum volume and runner length combination has been selected for aggressive low and mid range torque while opening up power higher in the rev range. The plenum volume is large enough for serious gains but is still compatible with factory AC. The Street version is suitable for any level of performance modification as we have conducted tests on completely stock engine/turbo/fuel system setups with approximately 9% gains in torque and power level, with the same percentage gain on highly modified setups running E85. For a fully streetable but aggressive setup while retaining the comfort of AC, the Street version manifold is the solution. For cars requiring more power in the upper rev range the street version can be supplied with shorter billet TGV's (lower runner section).