camshafts

[NoHachi]

Yes thats correct. The cams have one optimum flow point where they are setup to allow the biggest body of air into the engine without any reversal or blowthrough effects. Think of it as a big hump in the VE curve.
The effects of intakes and exhaust are seen in local peaks in the VE curve, but vallies as well. At some points the air bouncing around in the intake and exhaust (stated a bit simply for clarity) helps air in and out of the engine, but at some points it works against it. So you see that the Big hump (peak VE at peak torque) is increased in places and reduced a little bit further on.

Here comes the difficult bit: If you tune the VE peak from the cams onto the place where there is a VE vally due to intake and exhaust design, then peak VE may actually be lower then before. Think of it as an example of the systems design in engines, everything has to work TOGETHER.
One more reason to not just slap some parts onto the engine.

Be aware of one thing though: the ecu has a version of the original VE plot in its memory. It knows that when its at X RPM at a certain MAP pressure it has to be flowing X amount of air. When you start to deviate to far from this value the ECU just tries to interpolate from what in already knows. This doesn't have to work, basically its just guessing. Make sure you monitor Lambda en EGT+knock just in case.