I just read that article and the comparison they did is lousy if they're trying to compare an H-pipe to an X-pipe. The H-pipe system had 2.5" pipe and mufflers whereas the X-pipe system used 2.5" to 3" to 3.5" pipe and 3" mufflers. I think the comparison of the X-pipe system to the open headers baseline is interesting, but I don't think the H-pipe numbers are really very useful here. They should have used the same size pipe on both systems if they were trying to compare X-pipe to H-pipe.