Stihl MS-261 CM bar/chain oiling question. ... I just put a Chainsaw Guy mod muffler on it and it REALLY sounds serious now. The M-Tronic system brought it into tune ... The STIHL MS 261 CM is designed to be used by professionals for long periods of time, It is first choice when cutting down a large number of small to medium trees in a short space of time. When time means money the stihl MS261 gets the job done. Hit up the search, enter ms261 muffler mod and you will see several pages of results but the first page will be plenty, surely lots of pics and examples.... Yes the Mtronic will adjust, you may have to follow the reset (again teh search box is your friend). This low-emission, high fuel-efficiency STIHL MS 261 chainsaw was built for professional users and homeowners with large jobs. The hardworking 261 has a STIHL canister-style air filter element for filtering fine dust. Stihl - Aftermarket Muffler. Stihl - Aftermarket Muffler: Jacks is your Place! We have the Muffler you need, with fast shipping and great prices! For lawn mower parts and accessories, think Jacks!