Have read through pros and cons of metal pipes, overall, dosent really matter, so long as the metal is polished. Polished metal, or chrome dipped, so long as it's a decent wall thickness will be fine. As for the plastic, go for a run down the street and back, pop the hood, and put your hand on it. It aint cold, thats for sure.
The cold air that your POD is sucking in warms up pretty quick anyway, (especially if it isnt enclosed) because of the manifold. Thats why forced induction users go the intercooled path, as the temp of the air heading into the manifold is cooled down nicely first.