Correct me if I am wrong but usually a ticking noise is caused by lack of lubrication to the lifters. Once the oil pump gets some oil into the top of the engine it usually goes away. Check your oil level and make sure that it is not overfilled. You might want to switch to a different weight, depending on which type you use. I have not heard of ticking being caused by an exhaust manifold, unless it is coming lose and rattling. That is just my 2 cents though.