Curl,

I don't have any numbers to give you with the suppressor configured as it is now (short for hunting, with only a couple of modules), but with all 6 modules I seem to recall that it reduces the sound with 24db. The only way to make it as silent as seen in the movies would be to use subsonic ammo. So regardless of how big the suppressor is, you won't get it silent with regular ammo. But it definitely helps reduce the noise enough to help save the shooters hearing in the long run.

In other words, it is not suitable for politicians in elevators!