Fit with a spark arrestor, if the can doesn't have one and leave it at that..IMO
If you are supermotoing, go the whole hog, get the base of the cylinder skimmed to up the compression and free exiting exhausts. Oh and get lots of filters as the 350 engine, from memory is hours not miles.
Do it. Report back.
I really wanted to get one of those disc type Supertrapp cans for the DR350.... I actually kinda wanted one on the GN125!