Drilling the restrictor will add volume but really only enough to make a 1.5" ram work well. The drilled restrictor should put out about 2-2.5GPM which is great for a 1.5" ram. The 2" ram works best with roughly 4-4.5GPM.
In that's case I might have a 2" RAM for sale, I know its overkill but I got an awesome deal. Its now in trade or barter