Did you try it with the VDC off? U should notice that the shifts are smoother.
It seems a lot of people on this site are "afraid" or "discourage" people to drive with the VDC off
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..And they are right! If you are going to disrespect the car it can be horrible. I don't race and I don't shift passed 4000 rpm...In the snow/rain/ice/cold the VDC should be on. That being said I NEVER had it on with my previous car G35 6mt and I turned it off day one in the 370z.
The shifts are much smoother with the VDC off