Took my M6 to a local dyno day with a variety of other bimmers. We did several pulls in 4th, 5th and 6th gears, M6's best result was 409 whp, which seems short of 500 hp at the crank even with 20% drivetrain loss (I thought SMG would be as efficient as a manual, guess it's closer to a slushbox)
Dyno was DynoJet, which seemed to give somewhat optimistic numbers for all other cars.
I don't have any aftermarket software on the car, so maybe (hopefully) it just didn't like being dyno'd
It had all sorts of ABS, DSC faults while on the dyno, all cleared after 5 minutes of driving.
Here's the video: http://www.youtube.com/watch?v=PuZFHmyqcow, M6 is at 5:26 there, but the quality of the video makes it worth watching whole
Dyno was DynoJet, which seemed to give somewhat optimistic numbers for all other cars.
I don't have any aftermarket software on the car, so maybe (hopefully) it just didn't like being dyno'd
Here's the video: http://www.youtube.com/watch?v=PuZFHmyqcow, M6 is at 5:26 there, but the quality of the video makes it worth watching whole