Originally Posted by bmwktmbill
Actually got one on order.
If I read the reason you have added the flow info correctly you are thinking it could be the cam kicking in at 5000rpm? Had a little experience owning cars with cranky cams and the way this changes bang on at 5000rpm regardless of throttle or load makes me think timing advance changes at that point, its also a crisp edge unlike a cam which ramps up a little slower.
I agree that a faulty plug or cam timing out a bit would make this much more noticeable.