I've been meaning to post a video of this system, connected to stock mid-pipes, for some time. It's "filmed" with a smartphone so the quality isn't that great, but you get the sound fine, although you may need to turn up the volume depending on your sound system. Cold start with windows down. Unfortunately I cut the video before the rpm dropped to normal idle, which is quite a lovely sound itself, so I'll try to remedy that in the near future.
The HP was installed at 475 miles, so about 3k on it - it's opened up nicely.
http://gallery.mac.com/ennislaw#100322
pge