The muffler is used as a structural element in the OSSA's innovative design. I have never opened an OSSA muffler. The photos in the Image Carousal came by way of a friend.
Some bikes came with carbon fiber Termignoni mufflers. Back in the day, these mufflers used to be offered on eBay direct from Italy for $1629 USD. Note that there are specific ECU maps for bikes with Termignoni mufflers. Also, note that Termignoni is spelled wrong in the map names. There is a thread with photos on Trials Central showing how to repack the Termi, but if you have one you probably already know how.
OSSA Head Pipe
I am including this photo just because I have it. Note the amount of carbon soot inside. This was taken right after I bought the TR280i when it was running extremely rich.