Drilling the holes in the Rod throws reduces the rotating weight. Like making the big end of the Rod lighter.
Reducing the OD of the counterweights essentially reduces the weight of the crank. When you do that, you lose the weight to make the crank balance. To correct that, you either have to use external balance, or add Mallory to get the weight back in the counterweight. That way, you have enough weight in the counter weight to internally balance the crank, but you have reduced rotating inertia.
I haven't weighed that crank but it's pig heavy. So just getting some bulk off would help.
If I had any balls at all, I'd run aluminum rods. Bill Miller swears up and down I can do 50k on a set of his aluminum rods on the street before they need to be looked at. If that's the case, I'd turn the counterweights down until I touch the Rod throws and then add the Mallory.
