Surely the point of fitting a performance filter is to gain as much performance as possible??, therefore a performance cold air induction system would seem to hold the advantage , even though you wont gain much power its better than drawing in hot engine bay air and actually losing a small amount of power,, have you ever noticed how much better an engine runs on a cold day?,thats because its getting more oxygen due to the denser cold air, as stated in my original post the OE filter setup is very efficient, thats why messing around with the intake gives such small gains,if any!, you seem to suggest that fitting a under bonnet cone filter caused the car in your photo to "go like stink" if so why would car manufacturers go to the bother of fitting ducting as standard if they thought they could get away with the cheaper option of just bolting a cone filter on, i'm not suggesting the car didnt go like stink but i am pretty sure that it was nothing to do with fitting the cone filter .
The following leads me to believe that ALFA gave the induction system quite a lot of R&D!...."The Variable Inlet Control causes the air intake (plenum) to shorten its path from the intake trumpet to the valve bores, again when the engine reaches a pre-defined RPM. This works on the principle that the air intake length is a tuned pipe that when operating at its ideal frequency-in tune with the valves, will allow a smooth and even air flow, and will assist with filling the cylinders efficiently. This works in a similar method to the tuned exhaust system on all modern cars, where the exhaust system creates back pressure to pull spent gasses from the cylinder bores. The variable intake system uses the cone inside the airbox to reflect negative pressure waves back down the inlet. These waves are used to assist in filling of the cylinders. the variable inlet allows this to take place at different engine speeds.
The notable effect that these two devices have is that the engine will have a linear power deilivery from low RPM up until the red line, without the lack of torque at low RPM, and a kick in power at higher RPM, that is typical of multivalve engines as they come "On cam".
It is a type of Variable Length Intake Manifold"
As with a lot of other theorys Clive, this ones correct