I guess my age is showing. I had a Dodge CTD, and removed the silencer ring in hopes of getting a bit more boost, but nope, the only thing was a high pitched whistling from the turbo that really bugged my tinnitis. Scheid Diesel ran a dyno test to determine the actual benefits of removing the ring. They got the same dyno readings both with and without the ring. So noise is the only difference. I have a Chev D/A and it has a small turbo whistle at times, but not enough to bother my ears.
I looked into this also. damn near took the turbo off my truck, no silencer ring. i got an 03 lb7. from what everyone i talked to said duramaxs dont have them, just quiet turbos. if you really wanna hear your turbo go to xdp.com and get the 3'' turbo downpipe (like $289). replaces the junk stock flat pos downpipe.