Audi S4 B9 Forge Atmospheric Dump Valve. Had this fitted on my s4 a while now but Im upgrading to hybrid turbo so this will no longer work as the springs are not strong enough for over 500bhp. All the pipe work is cut ready to fit. Can be fitted in 5 mins.Instructions can be downloaded from forge website if needed. Message me for any questions. The item "Audi S4 B9 Forge Atmospheric Dump Valve" is in sale since Tuesday, December 29, 2020. This item is in the category "Vehicle Parts & Accessories\Car Tuning & Styling\Air Intake & Induction\Dump, Bypass & Blow-Off Valves". The seller is "caravantechnortheastuk" and is located in Darlington. This item can be shipped to United Kingdom.