As BDF has become the voice of reason what I think HE should do is put the bike up on the centerstand and run through the gears, using a video capturing device to record his findings. While he's at it he can also do a quick volumetric test in each gear
(said in his best reasonable voice).... my volume remains pretty much constant no matter what gear I happen to be in at the moment.Oh I don't know, in a tightly pulled basque your volume would be sure to decrease.
Brian