The crank pulley/harmonic balancer on my 03 wrx seems to be done for. The OE part is $288 but I have found lightweight crank pulleys from perrin and cobb for less than half the price. I am trying to catch myself up to speed on how the harmonic balancer works exactly (I know their purpose, just not how they physically work) and am curious what problems could come from simply bolting on a lightened crank pulley on a daily driven car. Any input is helpful. Thanks.