Trouble shifting

Driving around normal I really dont have much trouble shifting, but when I slam the clutch in and try to shift fast, I get a grind some of the time. I think its either the quadrant flexing, or a stretched cable. I've changed the tranny fluid and stuff

Could this be the problem? If so whats the best way to fix it. ie best quadrant/cable. I know stock is supposedly the best cable, but ya never know.
 
Common problem and I'm not sure there is a real fix. Don't quote me but it is something about shifting quicker than the syncros can adjust for a gear shift. I don't know exactly but someone else might be able to shed some light. Mine does it all the time when I run it hard. I know I must have all of these cool metel shavings in my tranny fluid now.