If you need to provide vacuum to the Resonance Flap - you need the Vacuum Accumulator, a vacuum source and check valve.I had linked this before & in this thread:
air intake/vacuum line routing - Pelican Parts Technical BBS
So the specific question is - what codes/performance issues are there if the resonance valve is deprived of any vacuum? The Resonance Flap(K) is electrically controlled by a solenoid (J) and receives vacuum directly from the Accumulator via a "Y" or 4-way connector.This is clearly shown in the linked diagrams from Wayne and identified by part name in his next Post in the link.