5.4 triton mileage improvement?


Viking with a Hammer
My 04 broke all studs when the manifolds warped from a plugged cat.
Oh, yeah. If the engine can compress the air in the exhaust to 200psi, and you have a 3" exhaust that's 1884 pounds of force on those header studs. My cat is about 6" across. So a blockage there can be 3768 pounds of force easy. That's why the potato trick never works.

Clean tight bolts can handle that with no problem. But header studs aren't clean or tight.