[Coley]

....like Geezer said....it depends.
do you have an (newer) aluminum intake manifold vs. the original cast iron?
If you are mostly a fair weather/season driver AND if the intake was a newer aluminum than I would add them and ensure that I had them in there to restrict heat.
I've read some very good articles on this by (Engine/Performance Guru) Bob Vizard who makes a good point with the fact that aluminum conducts heat substantially better than the cast iron so the need for direct exhaust heat with an aluminum manifold is not necessary in many cases.
My two bits.
Coley