Today I was going 100mph in 5th gear and when i looked down the shifter was vibrating quite a bit. everything else felt really smoothe (steering wheel, pedals, seats etc) I know the shifter vibrates, but this seemed more than i had noticed while just driving normally.

 

This is NORMAL. I have even seen and felt the shifter pulsate when I step on the gas. You have to remember the shifter is attached to the gearbox which is basically a housing with may different gears moving in several different directions. The resulting rotational force generates vibration which can be felt up through the shifter. Bottomline...don't worry there is nothing wrong with your Z.

 

well mine feels smooth and normal but if im driving lets say on 2ed and i go to 3000 rpm or more and i take my foot off the gass the rpm starts going down and my hand on the gear it feels smooth till it reaches lets say 2000 rpm i get a small 1 second shiver and this is on all gears but the shiver is on a higher rpm the higher the gear is.

 

Yeah thanks, its not every day that I go 100 thats exactly what it did was pulsate. Im used to the vibration while just driving normally, but this was more.