Getting ready to up my flywheel weight to 12oz. What are the risk of using the bolt-on weights as far as assuring flywheel balance. Stroker's 12 oz. is a bolt on type that has some "play" in it when placing it behind existing flywheel. I used shims to center the weight and drilled with press, but when tightening bolts slowly and alternating the weight shifts from center even with the shims in place. How true does this need to be? What will an out of balance flywheel do? Stroker evidently welds them on but does not balance them. Couldn't the weld itself play a role in balance? Thanks.