It would not be audible like a BOV, the air is getting recycled back into the intake path instead of wasted into the atmosphere. I don't know the exact differences but basically if there is a noise it will be happening inside the intake pipes not out into the engine bay. I prefer it without the sound really, much more sleeper that way. For those that want to advertise the turbo it can be done easily with a badge or something instead of hissing around the grocery store parking lot (I do like the sound unfortunately it has been ruined for me by people throwing BOVs on every econobox with a turbo.)