I kind of very quickly skimmed through the last several pages.
Not sure if this was brought up, but I noticed that the few dynos of E92 M3s that I've seen hitting near the 400whp benchmark all seem to be cars seeing A LOT of track time.
kaiv, joe@trinityautosport, and LateBraking are three examples of cars that put down HUGE power on a DynoJet. From what I see on the forums at least, their cars spend a lot of time at the track.
I just thought it was an interesting trend I saw among the three. Although probably way too small of a sample size to determine anything...