^^^ He speaks the truth! There is a nice rubber ring inside the pulley. Would there be any way you could add some sort of thick rubber lining to the inside edge of say one of these lightweight pulleys to try and fix it?

 

That's not eactly how it works... with a pulley that incorporates a damper, there's the inner ring (attached to the crank), a rubber layer, then the outer ring that the belt(s) ride on. Like a sandwich. As stated before, there are several companies making aftermarket pullies that are dampened.

If you want to start removing rotating mass, start with your wheels and tires, then on to the flywheel. Pullies should be last, if at all.