You may check this area too as shown in the pictures.
If the gap of indicated area is less than 1/4" when its cool, that is most likely where the noise comes from because metal expands after heat applied.
1. You can adjust the gap by realign OP since invidia flange holes are oval.
2. You can also adjust by front pipe hanger after tighen all exhaust together. I had to do this because PERRIN OP bolt holes are not oval.
3. Do both
