Is there room in the muffler to wrap the baffle with fiberglass?
A lot of pipes have done that. It knocks the sharp edge off the sound. Just get some household insulation fiberglass (Home Depot?) and wrap it around the baffle. Hold it in place with safety wire.
It won't last forever, but you can repack it when the stuff cooks out.
I wondered about the 2" head pipe diameter. Prob nothing short of a lot of dyno runs will answer that.
Very handsome system