This is the way I look at it, you weigh up a bob weight, get you number then add a % of over balance and then balance the crankshaft to that number. So in my view you are removing from the bobweight and adding over balance to the crankshaft. You didn't say what kind of components are being used here so I will use 2300gr ballpark for a typical 360 and you will remove 2gr of material per so 4/2300= .0017 or less than 2 tenths of 1%. cut away