what I did with mine was take out the tiny 1/4" outlet, welded that shut (was harder than you'd think with an arc welder... but it worked eventually) then took some 1/2" tube and put that out where I wanted it to exit then welded it in place and sealed it with JB weld. there's also a baffle in there that you can cut the center out of

the trick is to cut off part of the crimp that holds the muffler together, just cut off one end then slide the muffler apart (it'll require some assistance with a hammer), when you're done just slide it together again and weld shut