I have been contemplating this for a while. The outlet tube extends through the baffle plate. I assume (never assume) that the baffle provides some acoustic dampening. The baffle sits about halfway in the muffler section, above the perforations and below the top of the outlet tube. I was thinking of cutting the outlet tube so that it extends only about half an inch through the baffle. Not much of a modification, only a few inches shorter. I was also thinking of taking the baffle out and cutting the outlet tube much shorter. There is enough space between the inlet tube and the wall of the muffler to slip in a sleeve of thin fiberglass (glass pack). The fiberglass could be held in place by a very light weight, expanded sheet metal sleeve. I was also thinking of drilling out the perforations that I could reach (just a few of the lower holes). So, that would give a little bit better flow through and some sound dampening. The external part of the outlet tube would remain the same. I have to believe that some thought went into the engineering of the stock exhaust. It's been used for decades.