[CHANMADD]

Once the rotating assembly has been balanced you should not change anything..........including the pressure plate.......
Like I said before all engines have a harmonic imbalance felt as a slight vibe at around 2000rpm........that is why a "harmonic balancer" is attached to the crank.........to make those harmonics imperceptible.......
So out of balance does not make your parts junk.....it just makes them out of balance....
One piston though installed the incorrect way on the rod can make a vibration too.....
That's another thing , .....the rods should be balanced by weighing the small ends and equalizing them , as well as the big ends......pistons with rings..and pins...after gapping.......so they all weigh equal........