I don't have any experience with them, and I don't know of anyone who has. However, I don't see it giving 6-8 hp. From what I understand, the only true gain is in throttle response, and not in hp/tq. Though, at $170, it is relatively inexpensive (when compared to other 65mm TB's), so it may be worth a shot.
If I'm not mistaken, that's the company that Focus Central had making their TBs before they went out of business, and they're continuing to make them minus the Focus Central lettering on the butterfly itself.