Anyone calibrated the temperature w/this setup?

mike

Large Egg. Plate setter, inverted. Foil drip pan on plate setter. Grate. V-Rack. Approximately what is the difference in your experience between the cooking temp on the v-rack versus the dome temp? I've used this setup twice in the last two weeks (leg of lamb, turkey), and in each case, my dome thermometer said 300-325, but both items cooked much faster then I expected, as if the temp in the v-rack was much hotter. Maybe this has to do with the heat coming off the plate setter, or maybe it is the heat that circulates around the egg and on to the food on the rack? In one case I had my oven thermometer hanging off the edge of the v-rack but it read far less than the 300-325 that the dome thermometer had read.