Once upon a time ages ago when the air was clean and you know what was dirty I needed to change out the blown glass pack muffler on an extractor system. What was floating around in my shop was a Corvair Spider turbo muffler. It fit very well in one orientation and the inlet/outlet marking was hard to interpret so I welded it in that way. It was reasonably quiet and the motor ran strong so I used it at events with sound restrictions.
At one event an "expert" said hay Jim, you idiot, your muffler is mounted in backwards! I replied that it worked so well that I did not give a hoot. Later, my funny exhaust system was applied to a dyno setup to see how it performed and guess what? The reverse flow turbo muffler setup was born.
You never know what might roll out from under the old shade tree!
James H. Fleming