making a clang noise when i start my 2004 f150

From what I am reading allot of people say it's the muffler and or the cat making the noise from expansion at start-up !

Or you say popping, so did you cross a plug wire? Get two of them mixed up onto the wrong cylinders?

I have never heard anything like that when starting my cars with Triton engines. Popping might be a blown out spark plug.