MS261C -M Muffler Mod ?

[Dillier23]

Good evening. Looking into doing a muffler modification on my MS261C-M but haven't seen any that have louvers cut into the front of the muffler where there are groves pressed in already. Is there something behind the front of the muffler that would make it not a good idea to cut into ?

For some reassurance, the M-Tronic will adjust air fuel mixtures to compensate for additional flow?

 

[Dairyman]

I believe there's an internal pipe. I bought mine already modified. Reset the computer and your good to go.

 

[Jon1270]

I don't know about the internal construction of the muffler, but long parallel slits on the front would weaken it substantially and make it prone to be mashed in if bumped against a log.

 

[Dillier23]

I went ahead and tried it out. If it was done again I would not have cut the lower slot, the upper would have been enough extra in my opinion. It is louder, I don't particularly like that. The additional power is noticeable. I had been running an 18in bar, put a 20in on after the muffler mod and it will pull the longer bar better than a stock saw with an 18in bar. I made sure to reset the M-Tronic in a large enough log to use the entire length of the bar.