A few months ago someone posted info on a gadget (store bought or home made) that was similar to a washer placed in the exhaust pipe that can be swiveled to open or restrict the flow--and noise.
Any idea where I can find out more about this?

It was just a few days ago, I know they used to make adjustable lollipop kits but I have yet to find any online. To just make a lollipop itself and install it is pretty easy, just do a search on google images and you'll see tons of different types from bolt turn screws to different shaped washers welded onto bolts.  Do a search maybe you'll find an adjustable kit out there somewhere, if you are crafty you could easily make one using a manual choke cable I'm sure