Red,
Great timing on this post as I am in the process of removing my S/S mufflers (cutting them out) & sending them back to them for replacement.
Mine were great for the first 5-6000 miles then they started to get continually louder the socond season untill they are now unbearably loud after about 10,000mi. I inspected them the other day with my borescope & discovered there is virtually no packing left in them.
Now I have to say John @ S/S has been great about the problem & has offered to replace the mufflers with a "improved" version including all shipping cost. Can't expect much more than that.
While speaking with him I discussed this exact modification with him, he said they have never found it was ever necessary according to their their test results.
I also have that "fluttering sound" & also get a occasional tweeting or chirping sound from mine. (not a very cool sound
) So I would also be very interested in learning if this mod does help.
Thanks again Craig