I have the Carbonio CAI and APR Stage R1 Diverter Valve, and am very happy with both. I do get a moderate "woosh" sound from the diverter valve, but I disagree with the statement that it sounds like a Japanese car. The diverter valve doesn't make it very noticable. A Blow-off valve does. They are different. This is the sound that is in The Fast and Furious and such. And I would like to know how to get this "sound deaddening" material out and the consequences (if any). More sound works better for me!