This is the part that I wasn't sure of. The AC is an additional load on the engine, especially at idle or low rpm. But I don't remember the factory using a different cam if the car was equipped with AC, but most of the factory cams weren't really radical either. I'm not worried about vacuum, I'll probably be installing hydro-boost for the power brakes and steering. If I have to tweak the idle up a notch, that isn't the end of the world either. I'll definitely have the quotes updated to include AC but I was trying to get a little more background into what goes into it.