I wouldn't call it quiet, but while the car is running you definitely can't hear it, but you can hear it whir when you set the key and are about to start, which is a good diagnostic sound at least.
Lol. Try that with any other inline fuel pump that flows serious fuel. They all sound like a 4 stroke chainsaw WITH the engine running! Not to mention the rattles of the car that come with using one. I have ran 3 Walbros all at the same time and you can not hear them with the engine running.