Well, maybe the moderators can sticky this thread, or something - I hope it can grow into a good bit of information, sort of like a reference guide, that folks can use to find info on modding their mufflers, rather than seeing a new post in the forum every other day.
Here is a muffler I fabricated for the mill I'm building. I am using an 820 PowerBee motor, 135cc, as a power head for the mill. I had to build an exhaust pipe so I was able to have it exit away from the operator as it is running. The exhaust port on the motor is 2-1/2" long and 1" wide. I cut the flange out stainless steel with a plasma cutter and the pipe pieces from a piece of 2" diameter muffler. When I flattened the 2" pipe it spread out to the 2-1/2" I needed for the flang. I also built the spark arestorer from a piece of stainless steel screen mesh rolled up to fill the 2" diameter end. I used some additional SS screen mesh to make a containment screen and then made a containment strap from some 18 gauge steel that I used like a hose clamp to hold the screen on the end of the pipe. It holds the rolled up screen in the pipe. I used SS screen because it will never melt with the heat of the exhaust. I'm hoping it will sound real good!
Just another type of muffler mod if you want to call it a mod.
jerry-