i jus got a b16 w/ a stage 3 clutch put in my car and the motor only has 25000 miles on it and whenever im at like a high rpm switchin into 3rd it grinds but if do it like real slow like granny shiftin it doesnt...what could be the problem???

 

sounds like ur synchro are goin out

 

what kind of fluid do you have in the trans?
did you just have the clutch installed or did it come with the swap?

 

On your next tranny fluid change, examine the fluid or if you have a magnetic drain bolt, check for bits, chunks, filings of metal. Grey-ish filings-gears, bronze/copper-syncro, and shiny silver-bearings. People would suggest using a new tranny fluid with friction modifiers in it but it would only remedy the prob temporarily, might as well open the trans if you're able to and check yourself

 

maybe the shiftlinkage is bent. any slight bend will cause this

 

check your clutch hydraulics as well. if they aren't up to snuff it can grind.