Go Fast Bits BOV Deceptor Pro Electronically Controlled Blow Off Valve Subaru WRX 08-

A world first in blow off valve technology, the Deceptor Pro is based on the patented volume adjustable Stealth FX blow-off valve, but advances the design even further by featuring an industry first electronic proportional in-car adjustment of the blow off valve volume! The volume is adjusted by altering how much air is recirculated back into the intake tube.