John,
I did not notice any appreciable change in noise level out the exhaust when I changed up. It is probably a bit louder, but from the cab I didn't notice it. I have a straight-through muffler.
I DID notice a significant increase in turbo noise from under the hood. My PDR 40 did not have the silencer ring. The turbo whine was much more pronounced. On Sunday I swapped out the compressor side for one with the silencer ring. Much better. May still need to add a housing to my aFe intake system before summer gets here.
I'll be interested to hear what your opinion is.