ORIGINAL: cmoulder

Here is a picture from a few pages back, showing the header pipe and flex pipe arrangement (very similar to Don M's). I also used to have problems with mufflers loosening on OS 4-strokes, but I haven't touched this set-up since day one and it has been trouble free.

Depending on the application it may be a bit difficult to install and certainly more expensive but well worth it if you don't have to worry about it again!