My 05 4.6 2wd has an exhaust leak that I believe is near the egr nipple on the left manifold. I just changed the tube and nipple when I changed the egr valve a month ago. Everything feels tight when the motor is cool, which leads me to believe the manifold is bad.

I am thinking about shorty headers and was wondering if the 4.6/5.4 are interchangeable for a 4.6 engine. Would it be worth it to even do the swap on a 4.6, or just buy another oe manifold. I plan on buying the parts and having a shop do the labor on this one due to potential exhaust stud problems.

 

Found this on the modular fords site. I'm to new to the modular engines to say with any confidence.

4.6L 5.4L Exhaust manifold swapping