Here is a quick pic of 18 Stihl bar on my 025. It's only got 17" of usable bar. 3/8 Picco by the way. [ATTACH]
I've just gone to the junk pile and found one. I also cut open a couple and removed the cat and welded it shut.
I'm not sure you would want to run it with no muffler. I have replaced them with non cat mufflers.