Just an FYI.
I cut the baffles out of my 07 FLHTC mufflers playing with getting better sound from them.In the left muffler the baffle looks like a pipe around 6'long with holes in the sides and the end crimped shut.The right muffler has a full length steel baffle.Its two parts that join in the center.Inlet air goes through the first part then does a u-turn and goes out the outlet.The ends of the baffles are crimped down where they meet in the center.I wish I had taken pics.

 

So there is no fiberglass? Thanks for that correction.

 

I got hold of two sets of stock '07 mufflers off Ultras (65846-07 right and 65538-07 left). My '08 Ultra has the same mufflers on it. The right one has the two turn, half closed bafflesbut the left muffler is basically a dummy muffler with a screen mesh around the center looking into it from the header end, a closed baffle and holes drilled in the rear inside to vent the gas. The left muffler is louder than the right one and sounds different. The '07 and '08 49 state stockmufflers do not havecatylitic elements but the '07 CVO Ultra mufflers do. Stay away from Cat mufflers - too much back pressure. The new street legal/street performance SE mufflers have better flow than the stock mufflers but are a little louder and deeper sounding. The '07 and '08 stock Ultra mufflers are louder than the stock mufflers on my '06 Ultra and probably flow better to accomodate the larger engine.

 

My 06 EGS mufflers are both catalyst and both internally the same for flow and baffle design.
I'm thinking the older the better to a point , if your looking for better stock replacements.
Mick