The thing that makes the racket is the aspitator valve that was hooked up to the 2bbl air cleaner. While it was in there, it was quiet. or at least not loud.
But with a 4bbl on it now, I bet you just left that thing sticking up, and so yeah, that valve is awful noisy. And, of course, if you did that, then the Air pump has been sucking unfiltered air ever since. You can just cap that valve, which should make it a lot quieter.