Westcoast saw's universal exhaust port made for the MS261. Includes hardware.
I bought this for my ms261. Thought I already had great power, but holy cow did this thing ever kick it up a notch. I brought the saw out to my gold claim and ripped some 20" spruce boards no problem. The saw is an absolute beast now. Install was easy, just had to bend the screw hole tabs a bit in a bench vice, to fit the side of the muffler better. No regrets at all, highly recommended.