How tough is it to self install headers on a 02 4.6 because after looking at the underside and from under the hood it looks tough to get to the exhaust manifolds

 

Well, it's not easy by any means. I just did headers on my Expy with a 5.4L and it took about 8 hrs, split between a couple nights, I took alot of breaks. It may be easier on an F150, but I am not sure.

For me the passenger side was the hardest.