my plan is to have it balanced :) with the stock harmonic balancer and with the stock flexplate it's till having vibration. I've took out an engine and discovered that the crankshaft bearings are heavily "damaged", the oil is black with some metal dust... the shop have the balancing machine and my plan is to have my crankshaft balanced with the harmonic balancer and the flexplate together. or.. to spend some extra money and to buy the stroker kit...