Guys here is a tip on spark arresters. I cut out a metal piece of window screen and removed the end cap and cut the screen in the shape if the endcap and bolted it on for a spark arrester and it did not cut down flow but it will pass the stick test.

 

I rode silver lake 2 weeks ago no sound check just checking spark arrestors.You need an orv $16.25 and a state park sticker also $20 for the year.