Which year are you talking about?
Headers and cowl plenum were available as factory options in 67 and 68 (although both were most likely removed as options before the end of the 68 model year). They were in the trunk when the car arrived at the original dealership, if ordered. Both are rare. Some dealerships would not install them though, so that was then up to the owner. Headers not available as a factory option in 69.
Cross ram was not on any 67 68 or 69 Camaros from the factory.