Before you spend a bunch of money on a Flowmaster, give these a listen. They are Thrush Welded Mufflers, and they run 30-35 dollars through Summit or Jegs.
http://www.youtube.com/watch?v=TVtvDxbuO6c
http://www.youtube.com/watch?v=NtDNg2DW-HM
http://www.youtube.com/watch?v=mXVYxrQUmHk
http://www.youtube.com/watch?v=TVtvDxbuO6c
http://www.youtube.com/watch?v=NtDNg2DW-HM
http://www.youtube.com/watch?v=mXVYxrQUmHk