Scott,
First May I suggest you get a Real Heli Like an Xcell instead of that Vigor, then maybe you would be able to handle the power of a YS80...!
In fact I know of a Russian that would glady take your Vigor off your hands very cheap-as he Crashes them Weekly....
I know of another Russian That you can ask about the Muffler if you still want to try

You Know Who???????