FWIW I put Rush slipons on my '09 Ultra since new put Vance & Hines true duals and put in 2.75 baffle and it is very loud. I bought the larger baffle from Rush I thing it was around $60. Hope that will help your sale.
I have a set of 3.5 inch Rush slip ons that are takeoffs from my 2009 Ultra Classic. Mufflers sound good but were a little quiet for my taste so I replaced them with 4inch Vance and Hines. They are in good shape overall but do have some scratches and wear but nothing that is very noticeable when mounted on the bike. They are on the inside and underside. I am asking $175 shipped (conus). If you have any questions please feel free to ask.