Old Timer,
I think in your case, you are not dealing with silencer tuning but silencer restriction.
I had an old Dyno Port straight through silencer for my Husky 360WXC and it did make the bike much more powerful. However, I could not stand the noise. So I did some serious mods to the OEM silencer, including using larger internals.
I ended up with:
1) a slightly larger perforated tube in the first 10 inches of the silencer.
2) An open chamber in the middle of the silencer, with a small sheet metal disc centrally located.
3) a much larger perforated tube aft of the open chamber.
The modified muffler was much quieter than the Dyno Port unit, and it was just as powerful.
In my case, the OEM unit had very poor flow numbers on the flow bench. I more than doubled the flow rate.
Chris