I've been looking into doing some porting and polishing on my 2.8 v6's intake manifold. When I started looking around for info on the manifold, I found pictures of the upper intake seperated from the lower intake. When I looked at the upper intake manifold from the bottom, i was surprised to find 6 more throttle butterflies, one for each runner. They are hooked up to an additional actuator net to the throttle body. What is the purpose of the butterflies? Are the cruise control or something? Can they be removed for better performance?

Thnx