Philly, this old post should give you a general idea of how I attach a muffler to a stock header.  My bike uses a Mac header which is significantly different.  It's much easier to fit a muffler to the Mac header because the header is straight and does not have a step that reduces the OD.  In the old post, I show how to fabricate an adapter and shim it to fit the stock header.  It's not too hard but you will need a MAP Gas torch and a bench vice along with other basic tools.  See replies #3 thru #20 of this old post.

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1623048749