Thanks for the advise. Yes, I am using anti-seize on the spark plugs.

I just spent good money buying the correct factory-style fastener kit for the hi-po manifolds. As I mentioned, it is a combination of sleeve-bolts, studs w/nuts, and bolts. I'm thinking of giving the anti-seize a try first, and if that doesn't work, anti-seize and lock-washers. I was using lock washers previously, and still had problems.