I would say working as intended, but I am sure no one wants to hear that. There is a point as someone mentioned where there is a transition in the valvetrain. I don't have the rattle, but I have a noticeable stumble or hesitation right around 3k. I spoke about reporting back once I found the issue and/or solution, but I have not found anything but more questions.
The one thing I can say for certain is it happens mostly when you are light (very light) on the throttle. If you would dare to do so, use varying techniques to rev thru that range and then revisit the though.
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 2007 350Z NISMO #0618: Zerolift | UPREV | F.I. | Greddy | Competition Clutch | Injector Dynamics | Aeromotive | Pioneer | JL
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