Crockpot and antifreeze
Another vote for the cheap and easy way!
I cleaned a muffler off of a 61FX the other day, just to prove the power of the crockpot/antifreeze method to a fellow club member. His muffler was a disgusting mess, a carmel brown color from all the varnish. Not only did it remove all the filth, it also removed all the epoxy holding the exhaust deflector on. I have cleaned numerous engines this way, and never any scrubbing! The hardest part was talking the wife out of her crockpot....