The holy trinity of noise suppression is: 1) Expansion 2) Delay 3) Absorption
Sounds simple enough, but remove any of the three elements from a rapidly expanding gas and dB's will go up dramatically. Further, in suppressors physical size makes a big difference in dB output.
Personally, I own a DonnyFL Shogun...and I use it on a pcp pistol, All his larger suppressors have been able to handle every pcp I mounted on them. These things don't wear out, can be moved from gun to gun, so I respectfully suggest buying the best you can afford. And...as always, if you want serious silence, go big or go home!
Senile, but still functional...Kindly 'Ol Uncle Hoot