I lot of the compressor noise comes from the air intake. My other compressor has a big box that muffles the noise. If you take an old tractor oil bath air cleaner in Mount, it to your compressor it can quiet it down a lot.
Someone on a different forum suggested doing this so I have an old Belarus tractor has a blown motor (I bought for its front end loader) and I am going to use that oil bath air cleaner to make my compressor not as loud.
Here is a picture of theirs
And mine getting painted black.