my 03(one of the first 03's, bought in 02') has a knocking noise on the right side. I don't know if it is the "Piston Slap" I am hearing about. I took the car to ford and they said it is caused by a coolant passage on the right side is slightly pluged. They also said something interesting, if the car has a pulley put on it or an aftermarket blower, the motor will fail on that side. With that i didn't do anything, prefering to wait till the waranty got closer to the end. Another guy in town who got an early model, put a lightning pulley on his and intake and the whole 9 yards. His motor blew right away. Ford said they would replace the head on the passenger side. i was wondering if anyone had any similar probles and their solution.