where to drill a 2 inch hole in cowl

Just like MM2000. I used air,shopvac and a coat hanger cleaning out my dart. I removed the drain flaps and loosened the funk with thee coat hanger.Shoved the shopvac hose in one side and air hosed the other.Big mess also had to dump the shopvac 3 times.It took several attempts and a few hours to get it out.I bet your heater box is full too.