If I remember correctly, the main purpose of the Tungsten weight in the crankshaft of the Speed is to help smooth out the delivery of the power. It takes some of the "explosive" feeling of a standard V-spec away, making it a little easier to drive(smooth feel). To some people, this might be a good thing, to others, they may like the extra hit that a non weighted crank can give. Again, I'm not the foremost authority on engines, but I'm quite sure that's one of the main purposes of the weights.