a few things I failed to mention; then I will shut up
I put this at the major part of your air leak.
your spanner wrench; put your nubs at a full 180 degrees on your gland nut. in other words on both sides of your gland nut. and then I would add a third [for strength and stability] on the bottom or [better put] in the middle at 90 degrees. make it to resemble a ladle.
also with your pulley configuration; I would definitely run at the rpm you have been running it at.