.22 Wildcat vs .25 Wildcat noise level

I just talked to a friend who has had both. He says the 25 cal by a teeny bit. Hope that helps.

The noise should be higher by the same value as power value.
4,5 (.177): 24 J • 18 ft/lbs , 5,5 (.22): 41 J • 30 ft/lbs , 6,35 (.25): 65 J • 47 ft/lbs

I have and shoot both. With no moderator the 25 is louder as expected. The difference is noticeable, but not enough to surprise you. I have used the FX moderator sections. With just the two ends and no cup I would estimate that it drops the noise level by over half. I would consider it back-yard friendly at this stage. As you add cups it gets quieter but not by much. Maybe another 15%. I really se no advantage gain after two cups. I have been shooting mine with just the two ends and have been more then happy. I like to keep them short for handling. Just lately I have put a baffled NC on the 22 and a Huggett on the 25. Now they are extremely quiet and unless you set both on the bench and shoot one right after the other they sound about the same. The pellet impact is louder then the gun. Hope this helps. Your going to really like the Wildcat. They are great guns

I have a .22 Wildcat, and to be honest, it's pretty loud in stock form. I did shoot it in my backyard for a while without any complaints from the neighbors, though. I put a Neil Clague on it and it is very backyard friendly.