There's a pretty good difference between the PV1 and PV2 with the PV2 being much louder and also more compact. I don't have any audio clips but you can kinda hear my PV2 during a rallycross in the middle of this video clip from Jo Balsamo's site: http://www.imprezagirl.com/page7/page7.html

It's on the Fort Meade video, but may also be some footage of Heraclid's PV2 on the ERS video too.