sorry for the late reply
a few things with my extractors:
they whistle under engine load (like a ting ting ting sound that gets faster and faster till it just becomes a whistle at higher rpm)
O2 sensor placement was an issue with getting it tuned because it was too far back, too delayed and caused issues with getting the car to meet emissions standards (we moved it onto one of the joining pipes and it stopped the issue, but now i'm only getting O2 readings from one cylinder head)
i don't know if they sounded different before or after, nor do i know if they gave a performance gain, because i never ran the car with stock extractors (it's a gen2 liberty converted to an EZ30r)
sorry i can't be more help... if you guys want any more or different videos (other than what's on my youtube site:
http://www.youtube.com/blaeven)
let me know