With the stock pulley and then with the lighter one? Also I think it's important to lighten up the flywheel along with the pulley. If you take weight off one end of the crank you should do the same at the other end. I don't think any measurement taken would be valid without doing both the pulley and the flywheel. As for the stock pulley, please explain how it is in any way a harmonic balancer. It's a solid piece of iron with no dampening material in it.
Fred 95 300TT SGP Stage..Who knows..lol Dynoed 539.4 RWHP, 481.2 Lbs. Torque Pump Gas @ 17 Lbs. of Boost NO NOS!!