I want to refinish my gil exhaust manifolds. I have sanded down the bad spots and scuffed all the surfaces really well. Can I just use the Merc Phatom Black paint on them? Will I have to use an etching (epoxy) primer? Or will the manifolds get too hot for this type of paint? The manifolds are in decent shape, I just want to freshen them up.

Anyone every paint these aluminum manifolds? Do I have to worry aboout how hot they get?

I have a friend that took his to get powder coated and the place did a great job and they still look like new after two years. You might also look into maybe anodizing.

I would say that the part of the manifold you can see is the external water jacket, it shouldn't get above 212 degrees, so you are good to go with whatever scheme you want. There is a part down by the head where there is no jacket (bolt area) that can get pretty hot, but you really can't see it from the topside.