cut the stem in half...looks like its about four inches long...make it two..i did that with my TEC exhaust baffle on my 13 scrambler...i will see if id can find a pic....

 

 

 

or drill a few more holes till you like the sound before cutting

 

Thanks for posting the pics.

 

The high flow TEC performance baffle design is probably what your after... The larger bore gives a much deeper tone 😀
I had something similar which was made for the Arrow 2-1 on my 2010 865 Bonny some 8yrs ago. Gave it a very unique sound. Somewhere on the air cooled forum there’s a photo along with the specs for its manufacture.

 

Ok , Thanks I’ll have a look for it.