When you were a kid did you eat ice cream dipped in paint chips?! I know this sounds difficult but in order to comprehend the meaning of a conversation you must listen (or read in this case) more than just one sentence. Let me help you out. What tbundy is saying is why would someone want a big V-8 that has 200 hp and 300lb-ft of torque ( those are estimates most older V-8's have been modified) when a V-6 is available that is is 1/2 the mass and has comparable power figures, gets better gas mileage and will run with very little vibration due to the engine being properly balanced by engineering the proper size balance shaft.
In post #1756 you state that a V-8 "suffers a small degree of end-to-end vibration" and "simply uses counter-balances to eliminate the vibration."So you know that a V-8 is not perfectly balanced and someone must engineer counter weights to balance the engine, hmmmmm dont they have to do the same to a V-6? The only difference is on a V-6 the counter weights must be bigger. As a result of the processes involved in the manufacture of engines and engine parts it is logical to come to the conclusion that through the use of counter weights that a V-6 engine can be balanced to achieve vibration levels so close to those of a properly balanced V-8 that the difference cannot be felt only measured.