I'm wondering about
the wisdom of modifying a moderator costing 150 or 200 dollars....

Because:
I can readily believe that
my China guns are a little short on R&D and on quality materials. So, if their shrouds need some extra help with hair curlers, I'm ready to raid my wife's drawers....
However, a silencer from DonnyFL or Huggett or any of those outfits — it seems like that's all they do — and charge a price for it, considering it being
a glorified ballistic oil filter....
So,
IF more washers, less washers, a thinner or thicker felt, etc. would make such a big difference — wouldn't they have figured that out when they designed their cans...?

Now, I understand from reading the R&D posts of Silent Thunder Ordnance
that a silencer benefits from being adjusted to the amount of air being expelled by a shot. So, a higher power setting would have a somewhat different design than a lower power setting.
And at this point our silencer manufacturers could possibly gain an edge: Instead of offering generic silencers for a generic power setting (whatever that is) they could offer silencers for different power settings, say for .22cal — one for sub 15FPE, one for 15-35FPE, and one for 35-45FPE, or something like that....

If you have a gun
with a particularly high or low power setting, I would probably contact the manufacturer/ R&D and see what they'd recommend — warranty nonwithstanding of course.
I'd think DonnyFL would respond, he has to me in the past.
Just my 2ct. I have yet a lot to learn....
Matthias