I HIGHLY recommend hunting down the elusive PV1 (Power Vault 1 series). Occasionally, one will appear on the sales forums and it goes fast. Had mine installed new for about 6-7 years now and only gets better with age. You push more air with a S/C on a PV and you are really on sound-par with some V8s.
That clip with etl's PV is most likley A/V artifacting. Though, he could be running a PV2, which, IIRC, has some resonance due to a baffle/silencer welded into the pipe or something. I think most have cut them out and it's mo'betta now. Maybe someone here can vouch for the PV2 that has one, though I have never heard one of those in person.
Gary Noonan
'01 S/C VX / '18 Forester XT