Cool. Is the copper going to come into contact with the engine? This was what I was concerned about. The ambiant temperature of the engine bay is not as much of a concern as the engine transfering heat through direct contact into the manifold.

The best way to design a manifold is to remove ALL heating capabilities, in other words prevent any hot air from getting into the intake. There is really no way to remove heat lower than ambiant temperature from the intake air, this includes intercoolers. Intercoolers lower charged temps to ambiant temp. The only real way to lower the intake charge are methods like methanol, alcohol, ice pack ect.

Look at all the new intakes on the 2.5 GT, they are made of composite. The reason for this is to keep all the engine temperatures whether it be direct contact or radiation heat from getting into the intake charge.

Tell you the truth I hope your method works! I have been studying intake designs and intake temperatures for quite a while now and I plan on going with a carbonfiber intake for its strength and its low temperature transfer rate.