Originally Posted by Aussie Steve
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.
Without knowing the cam specs I can't comment if its normal to have a hit at 5000 rpm. I can tell you that I have put different cams in my hot rod V8's over the years that had a lot of overlap and were poor to average performers at low rpm. They did have a noticeable hit in the upper rpms and absolutely screamed to redline. Sometimes if you actually dyno the vehicle you will notice the lower rpm power isn't that much different than before, but the new cam brings on the power so much harder up top you feel it in your butt dyno more.