Quaboosttro

and I think it was about time! I only saying that because the fuel pump had been singing a sad tune on occasions. Anyways, after shutting the car down (keys out of ignition) today after a drive I noticed a different sound coming from the rear end of the car. It sounds like an intermittent fog horn in the distance... actually thats what I thought it was at first, lol! If I shake the car, the sound moves with the car.

Does it sound like a little extra air got into the lines?