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 creates an appealing atmospheric blow-off valve sound and improves turbo engine operation. The Turbocharger bypass diverter valve is made from a plastic and metal blend, boasting wear resistance and structural stability for long-term application., Manufacturer: VNSMM