i have caught a corn field on fire with my underbelly exhaust system.
that was not fun, so i installed a upright muffler
but as others said it was loud and in your face and had to have a cover if the tractor was ever left out in a big rain
i later put the muffler back under the belly of the tractor, much better.
i just watch the muffler when bushhoging and try never to stop the tractor in tall dry grass.
you just have to be aware of where you stop as the muffler is hot.
i understand back in the day, they made a heavy mesh wire muffler screen to protect the underbelly muffler from grass, but i have never seen one, so they must not have worked very well.