5 star's dyno can't show 450 at the crank because they use a chassis dyno. The factory claim of 450hp is the baseline used by all tuners. You are correct that all dyno's are going to give different readings. Even within the same type and brand of dyno the readings can be different. They all have a +/- accuracy factor. With that in mind either ford's rating of 450 is under rated or the drivetrain is extremely efficient.
this is my last post regarding this since we are getting no where. You need to take ford's 450hp number, and throw it away, it is meaningless in this thread, period.