Hi Miles have done this for years. I weld a pipe same dia as the lower then drill out the pipe. Install turn downs on the Granny Chair wings. Or drill out the welds that hold the metal in the stock extensions and use them. You could take the metal out of F6B slash cut extensions and then drill a hole in the end of the muffler the size that makes you happy. I have seen most of the end cut away. Have fun..