1997 F150 4.6. How hard is it to remove and replace the manifolds. i get a clicking sound from them. I searched and saw a lot of threads talking about replacing the manifolds. what is the best way to remove the olf manifolds? i know the machanic that I use just cuts the nuts off and goes from there. Could I get an impact on them and try that way or are they likely to break off doing that? anyone have suggestions on headers vs manilfolds or what headers to get. All help is great.

 

The best way to remove exhaust manifolds on these trucks is very carefully with lots of PB Blaster or some other penetrating oil. Soak the studs with penetrating oil hours before you plan to remove the manifolds and then turn the nuts very slowly and methodically. The exhaust manifold studs often stick and it is very easy to break one off in the head. For that reason, you should avoid using an impact wrench. Also, it is easier to reach the manifolds on your truck if you remove the front wheels and the front plastic wheelwells.

 

cogden is right, soak them good. i broke one off in the block and it was a pain. i had to remove starter, plastic inner finder and jack the motor up to get that bolt out. as for the header vs manifold question, its up to you. shorty headers will give you better power in the higher RPM's and long tube headers will give you lower RPM power. i have pacsetter shorty headers and they do make the truck sound much better and help out with passing gear at 70mph.

 

Did you READ the threads??? There is lots of good info in those threads and all your questions are answered there already, IMHO.
I have added my experience in two or three of the exhaust manifold threads.