I've been reading up on the worx dual stage bov. I guess that's the one you're talking about. Mine is arriving in a week or so. It's my understanding that if you want the sound at lower rpm's, you lower the spring to it's lowest setting. i believe that is the one lower than default. I don't know how many settings there are.... possibly only these 2. The lower setting reduces the spring tension I think and allows for the valve to open easier. Anyway, I tried to attach a photo of the spring I downloaded from another forum. Hope it worked and helps.