I want you all to read this very carefully...
The sonic boom is VERY TINY.
A 180gr .308" bullet from my 30-06, going ~2700FPS... and it sounds like a .22lr.
Most of what bugs people while shooting is the muzzle blast - even just getting rid of the muzzle blast is VERY, VERY helpful.
The sonic boom on my PLR-16 .223 is a joke - barely anything at all, sounds like someone downrange (the noise is reflected) dropped a book on concrete.