Forge Motorsport Dump Valve for Subaru Impreza 2001 Onwards, Including the 2009 GR STi. We recommend servicing your valve every 3 years, or 20,000 miles, whichever comes sooner. An Alloy Atmospheric Dump Valve to fit the Subaru Impreza 2001 onwards models including the 2009 GR STi. Made from billet aluminium and hand polished in the UK, this atmospheric diverter valve dumps the charge-air to atmosphere creating the "Whoosh" sound most commonly associated with rally cars when the throttle is lifted.
This increases both quicker throttle response and higher clamping load to maintain boost pressure more reliably. In The Box: 1 x FMDVSUB01 Valve 1 x 34mm Blanking Plug 1 x Forge Sticker. If you wish to tune this product to fit the needs of your engine, please see the spring tuning kit below. This fits the following vehicles: [car_parts_fittings]. We are a small business and as such there may be occasions when we are unable to fulfil the order due to issue out of our control so please bear with us!