This is one of the easiest mods. Buy 4 or more stainless steel washers, the size doesn't really matter. Take the stone off the lower platter and arrange the washers on the platter so they are more or less evenly distributed, and put the stone on top of the washers. This mod was proposed by Scott on Pizzamaking.com. He suggested that by raising the stone slightly off the platter, there would be a slight buffer of air between the metal platter and the lower stone, which would reduce the transfer of heat to the lower stone. I did this mod right after buying it and have been pretty pleased.
DO NOT USE ZINC PLATED WASHERS. Zinc is a bad chemical, if you put it on the platter, once you heat it, that can release bad fumes into your pizza oven. Don't risk it. Spend a little extra and get brass or stainless steel washers.