hey, i have a 88 iroc with a 5 spd, its 305 tpi. anyways.//// when i shift at high revs like doing a quick shift, sometimes it grins, and its not the clutch cause i put in a new one like a month ago, Center Force Dual Friction,.,.. its when i shift really quick like throw it.... cant figure it out, never did this before....

 

sounds like the clutch isn't fully disengaging or you left foot and right hand aren't in synch.