Installed my cobb cat back exhaust last week and was hearing a screeching noise under heavy acceleration checked everything for leaks and had none. I removed my manifold heat shield and found the bottom of the cylinder head black and the manifold stuts/nuts loose (hand tight) so I tightened them and it was still making the noise so I removed the manifold and found the gasket is warped and leaking. would loose bolts cause this? I ordered new studs nuts and gaskets was hoping that would fix it. car has only 20,000km and I have never had the manifold off before so it must have come from ford loose and slowly got worse with vibrations till it leaked and I noticed, just strange how I didn't hear it until I installed the cat back.
