Balancing an engine

there is no doubt that an engine that has been balanced is going to be better.and yes it should be dun but if you are buying aftermarket parts i'm sure there within a certain degree of balancing.and could be run.I have dun it.and you could tell a deference.buy the way it revved and run.wen racing it.because that same motor was taken apart and balanced only with just new bearings and run about one tenth quicker.so if I was going to do any hard thumping on it. It will be worth the extra money spent.talk to a class racer every motor they build is perfect in every way that's why they can rev higher and last longer if and wen they blow a motor its usually a part failure.....and thats my 2cents worth if its any help..Artie