Mine is the standard set up so far, the most front mounted flat box is like a flat sarnie box and may be the weakest link.
I do know PDT on here used to run a Pipercross Cone on the very front of his Dbilas set up on his Ed30 instead of the flat box arrangement.
If (when) I go beyond Stg1, may have a look down that road for better flow.
I think the Dbilas quietness is likely due to the pipe thickness, the cast metal tubes are like coffee jars in terms of their build, so guess air does not howl/whistle through. That said I've not held an ITG or twintake to compare.