It's been done, sort-of. There was a time when the fire-danger Nazis got real strict in our favored riding area, and would write big three-digit tickets (this was before my time, so that was a lot) for anyone who didn't have a spark-arrestor, even if their bike was still tied-down in the truck. One of my dad's buddies took a spark arrestor, took out all the insides, and hammered it over his bike's stinger until the end of the thing was only about an inch further out than the end of the stinger. It was like the end of a horn or other brass instrument. I hear the noise was positively biblical.
