why dont people do this? with welds in some places and un heated metal in others and unseen stresses pulling at eachother. i would imagine you could reduce cracks and have a manifold last alot longer. plus it softens the metal and could allow for more flex.

 

you usualy anneil metal to make it softer so you can better work with it. when you have a manifold that frequenty sees 1300ºf, i don't think it honestly matters.

 

Or up to 1600 if you are a bit lean or really retarded.

 

On cages and stuff like that you can either send it out or warm with a torch until a dull red. Then let it air cool or even better yet slow down the cooling. Does it matter on a manifold. Most likey not, but does it hurt, most likey not.

Randy