So I finally went down to pick the screens and material today, and installed them in the mufflers.
Easy install with the Fullsac screens- they length is just right, and the fact the springy screens compress makes it much easier to install since the packing material just sits loose around the screen. Had to filddle around a bit, and slide it in nice and easy while keeping the screen compressed in order to avoid the packing bunching up.
So at idle, it definitely sounds deeper. I just rode around a country block, so I don't have a for-sure opinion, but my first impressions are this did just want I expected it too- still has that Rinehart sound, but now with a bit of the edge taken off. The 4" Rineharts never sounded too "tinney" (like the 3.5" do), but any tinniness is much reduced or gone.
I'm glad I went with the 1/4" thick material vs the 1/2" stuff- I think 1/2" might have muted it too much. I just did one wrap around.
Overall, this little mod worked well. I'm off work for 2 more days and the weather looks nice, so I'll do a couple hundred miles in the next 2 days and will update my thoughts then.