I stuck with the original manifolds and had them machined as they were warped. I used anti seize on the bolts to keep them from galling again. Also just a heads up on my 01 the bolts were over torqued at the factory. The bolt shoulder was driven into the head and messed up the first few threads which locked the bolt into the head. Out of twenty total bolts I had seven which I had to extract. Use a fluted extractor. If you have to drill out a bolt a company does make a drill guide kits. The kit cost me $600. After I was done I sold it to a local Ford dealer for $300.