Always change the throwout when replacing the clutch. If you have it apart you might as well change it. Grinding noise when pressing the clutch pedal all the way down is the throwout. It should be a little quieter if you push it in up until right before you hit the floor and then it gets really loud when fully compressed. This is because you are shifting the race when things become tight and you are operating outside the groove in the bearing. Sach's clutch kits are the best. Very tight clutches and will outlast the OEM. The best way to change a throwout is to take it somewhere that is trans specialist unless you really know what you are doing. A properly centered press is required to get the best fit and longest lasting bearing.