Borla S muffler ringing noise

[Jonezie]

I bought these Borla S types used. Past owner said 10000 miles on them and they are clean. However, when I step on it, I hear what I describe as a ringing noise. I have been told that it's the mufflers, but nothing specific. I put my vacuum cleaner on blow and connected it to each tail pipe to blow in and the only hole is the tiny water weep hole. Anybody else have a similar issue? I am probably going to buy brand new ones, but I want to be sure the same problem isn't going to happen again and if a bunch of people say they hear the same thing, maybe I wont buy Borla. The vid is too large to upload

 

[Pete fender]

Ringing noise may be caused by a broken or defective weld causing a loose or vibrating baffle.
Any brand muffler can.
Any part can.