I am not an professional engine builder like moper so listen to him but why must you rebalance if the pistons weigh the same or within a few grams? I think everyone assumed theres a big weight difference in the pistons which may not be true.
Between trw old style pistons and new aftermarket , there is a whole bunch of diiff. in weight . If so , I`d rebalance , if really close , I`d go with them on a street car.
