Lightweight crank pulleys?

[Kevin 1G Drummer]

Balance shafts reduce overall engine vibrations, where as a crank damper reduces vibrations more specific to the crankshaft.

[niterydr]

Originally Posted by Kevin 1G Drummer

Balance shafts reduce overall engine vibrations, where as a crank damper reduces vibrations more specific to the crankshaft.

Exactly. The balance shaft is there to not transmit vibrations to your ass when you are sitting in the car. The harmonic balancer is there to cancel out crankshaft vibrations.