Thunderheaders, Bassini, D&D,and Supertrapp are all good exhaust systems. You need to pick the one that sounds the best to you. Better make that decision before you buy. Check the classified here on the forum.
Sound is so subjective and one persons "great" sounding pipe is anothers horrible sounding pipe. I have run Rinehart, Bassani, D&D and Supertrap 2-1 and each also sounded quite different depending on the engine configuration. I have also run many different slipons and true duals and haveinstalled many onthers bikes. For performance, D&D, Bassani, Supertrapp, Thunderheader, Rinehart are all pretty good, but if I had to pick the top two, D&D and Supertrapp. Oh, and for fit and finish, I don't think you can beat D&D and at the other end of the spectrum, Thunderheader. They have always had poor chrome and fit IMO.