Bone,
Each header was tuned, so it wasn't a just throw it on and see whats up kinda deal. Kenny, the guy who tuned them is a good friend but also a competitor of mine that is a very smart guy. He didn't do this test to bash any product. He's done a bunch of tests with all kinds of parts, Intake manifolds, intakes, etc etc. We spoke about this for some time last night, and you can clearly tell the Bisi header makes less up top just from the fuel map. Theres nothing wrong with the valve springs, the power went right back up when the other header was put back on.
I don't know bisi, and do have a level of respect for him, but all of his products ive personally seen haven't worked up to the marketing and hype around them, esp when you consider the price difference between them. I feel sorry for the poor smucks that buy his BS. There should be a difference between an $1100 header and one made by a 14yr girl in a sweat shop.