Mazda says that the resonance chamber increases mid-range torque:
I'm inclined to believe them on this.
Note, we are talking about the number 2 resonance chamber...
And yes, the general concensus is that Mazda is correct, remove the resonance chamber, and you loose torque.
In theory, you might gain a little HP at the "top-end" by removing the resonance chamber, but overall it simply isn't worth the loss to remove it.
OF further note, the stock Air Intake is a true CAI... the intake you made Chris6, inspite of appearing to be a reasonable heat shield.. is still sucking air from the engine compartment.. into other words.. you made a Hot Air Intake out of a Cold Air Intake.
Run your car on 1/4 strip. Find out how fast you can go. Then put the stock intake and stock resonator back on, find out how much faster you go....