ok, problem solved! the tires mounted on the car were the wrong size. the last owner i assumed wanted to lower the car so he took the easy way out. installed on the car were 215/55/16 tires. i replaced them today with the factory dimension 225/60/16 and the humming noise went away. the car rode better also. i picked up some eibach springs today. i am going to order the kyb agx next week.