I suspect the Air FILTER Resonator is used to provide a clean air supply, not much else.
The newer Dawes have a choice of ceramic balls for very small $$ extra.
BTW I have the Dual Dawes setup complete, and it appears to work as advertised. Boost pressure limits are lower than what I set off-line but that is a fairly simple adjustment (or not!!)
I disabled the high valve to check low maximum, then the low--not much to see there.
We shall see!!!