like the title states, i replaced the clutch master cylinder on my 1994 gsr bc it was leaking inside the car, well the pedal feels alot firmer now and has alot of pedal force, but i noticed now it shifts really hard at higher rpms, and grinds when shifting fast at high rpms. before the master cylinder was replaced, the trans shifted like butter and no grinds wat so ever. Clutch is releasing all the way, i've tried adjusting the pedal free play, still nothing. I've even bleed it some more hoping there was still air in the system, but nothing. Any help?

 

I've had the same problem before, I fixed it by doing an EXTREME amount of bleeding. sometimes when replacing those, air can get in right at the top, and then you essentially have to bleed the whole line out before there is no air in the line.
If there is no air in the line after lots of bleeding the line it is possible that the slave may be bad as well, or maybe the master you put in is a dud.