Your muffler is shot does not surprise me, so was mine and I just went to the dealer and had them sell me a after market muffler with a new upper pipe. If you think it is loud with a bad muffler putting on a straight pipe will make you get a new muffler as it is super loud without a muffler. The other part is the engine still requires some back pressure or you will really having it blow soot all over the place.