Having the belt snug against the bevel box pulley is OK. That pulley is hardened steel and the only noise you get out of that one is from the 90 degree gears on the inside, hence the gearbox whine.
My first (2012) rear pulley had the bolt on flange added to it. Everything was made of aluminum so if it was not set up just right it would squeal. I wore out three before I bought the Super Max rebuild. It has no outside flange and makes no noise. In that case I set up the belt so it just barely hits the wheel side flange and for the most part just floats as it does have a tendency to move about during acceleration and deceleration. The front pulley doesn't seem to care one way or another.
