ok.Jet sizes. Same as yours--55 and 155. I still have about a third of a white spacer. I didn't mike it last time it was out. I was still backfiring until I put the new muff on. I am using the stock airbox and filter.
As to model of muff..here's the link
http://www.jpcycles.com/productdetail.aspx?PID=4500055&cs=Metric&GID=593B7A2F...As far as mounting, when I took the old stock muff off, I had a hard time getting the copper sleeve out. I managed to mangle it a bit so that it didn't fit. I had some metal pipe tape and I coiled it around and put it inside the muffler to help seal up the area. After test fitting it a few times, I used the high temp red RTV silicon sealer and ran a big bead of the goo around the inside of the muff and slid the muff onto the pipe. Used the muff clamp but ground the "ears" off of the one side so it would clamp tighter. VOILA....one nasty-sounding Savage. Oh and btw....I am now getting 58 mpg...10% more than before.