Also you might have a massive air bubble in there, which might be caused by incorrect coolant filling procedure or thermostat installation (you must remove the bleeder screw on the thermostat housing when you fill coolant and have the jiggle valve at the top of the thermostat when you put it in). Also, "aftermarket" thermostats are crappy and the seals perish quite quickly. The top radiator hose should be a bit hotter than the bottom one after driving around for a bit.