I have searched and could not find any aftermarket dual port muffler setups for the Stihl 036/360 saws. I decided to just jury-rig up one myself. I don't have a welder, so I was thinking of screwing it or riviting it in place. I settled on using screws so that I could easily remove it to clean/change the spark arrester screen, or to enlarge the port hole after further testing. I simply started with a circle of metal and bent it down the middle to form the basic shape, then bent flaps on the sides to accomodate screws. The spark screen is sandwitched in place over the port hole and held by both screws. Fired it up, adjusted the carb slightly, and it sounds great. Going to buck 2 pignut trees up with it in the morning to see how it cuts.