Firstfives.org

would improve idling? just a forethought?

If you have a poor idle, porting your exhaust ports or manifolds is completely unnecessary in diagnosing your problem.

i mean, at first it wouldn't have a benefit, but from my logic = if you port your exhaust manifold, you have more volume for the exhaust to occupy, therefore less of your exhaust will escape back into you engine where combustion rx's take place. Thus, more oxygen is combusted and less surges will develop as a result.
just my rationale though

Um, no. There is such a small volume of exhaust gases at idle, that the normal diameters of the manifolds and tubing are the farthest thing from a restriction.

Think about it like this - use a fire hose to dribble some water on your flowerbed. Is the hose a restriction? Nope.