They do but...
When hired help get a hold of stuff they use it and abuse it.

Does any one know how to figure the size of tubing to use in a muffler for this thing?

It did not come with a muffler, so I'll need to make one.
That brings me to another point of interest.

I bought a propane torch from Harbor freight the other day and some rod to weld aluminum with.
I practiced on some flashing I had laying around and it was very easy.
The torch looks weird but it is the best torch I have ever seen for a propane bottle.
I think it was $12.00 or $16.00 and has a lighting button on it. They only carry one torch for bottles.
I was really suprised they both worked so well.

No preheat. Lay the rod on the metal, add heat and when it starts to melt move the heat forward.
The rod melts just before the base metal gets to hot and melts.