Universal Auto Aluminum Part Turbo Blow Off Valve Recirculating Diverter Dump Valve 25MM Or 34mm Bov Sound. prolongs the life of your turbo charger, and being a recirculation valve does not cause any errors in the vehicles ECU. This is the best valve for performance and efficiency and will give you a nice, but quiet metallic 'chunk' sound on lift off, but it will NOT give you a 'swoosh'. The blow off valve adapter helps produce a pleasing atmospheric blow-off valve sound and optimizes turbo engine. The Turbocharger bypass diverter valve is crafted from plastic and metal, featuring wear resistance and shape retention for extended service., Manufacturer: AKPOUYC