I am looking at getting a Mac Muffler of other type after market muffler for my OS61FX to try and ad a little power. Can't use a tune pipe. Any help on this one? Thanks Gary

I have owned two 61Fx's and put macs mufflers on both of them.

I have had nothing but good results. Both engines gained a few revs but the biggest change was a quieter engine with exceptional response.

I first went to this muffler when I lost the back half of the first engine. Then when this one died from too many flights and one last one into the asphalt ibought a new on and bought a macs muffler at the same time.

Try it you will like it

thanks for the info chazman

Gary,

Take a look at the Ultrathrust Mufflers.
http://www.pspec.com/muffler.html
I have never used them myself but have seen others with them. They seemed to work well and the owners liked them.

Eric