I bought mine without a spark arrester and it ran ok. I recently put a new tip on it for the look and sound. It may have just been me but it felt like it ran a little better with the tip. It may have something to do with the back pressure but not sure.
Took them out of mine, hated the sound so I reinstalled it. You'll be fine running without it, people have slip on mufflers with no programmer. May want to watch if going to state land with out baffles.