Update.. Spoke with Manny from Mac performance regarding the design of the prochamber.. According to his description, the prochamber is NOT a resonator nor is designed to dampen or cancel sound frequencies associated with resonance drone.. The Prochamber's sole purpose is to increase torque and HP by merging the exhaust pulses/gases into one area in order to smooth out the exhaust pulses and improve exhaust velocity and flow.. Also the Prochamber design has no tubing in it's enclosure whatsoever, but rather uses 3 reflector plates instead to help balance exhaust gases for optimal power..
At any rate, that was the info provided straight from the manufacturer..