Wilma, I took the air dam off after noticing that it was nearly touching a kerb in a car park. Not the thing i would expect in a 4x4. When I removed it I was astonished to see that it hides a pipe going into or coming out of the engine compartment. I want to know what this pipe or "orifice" is for.Grumps, You must be right, surely,but if you look inside the engine compartment you will see a wide metal pipe going down to near the front axle. I think it joins "the orifice". The Orifice pipe has a fine thread in it so it could be used perhaps for connecting something to it for engine maintenancce. I have never seen anything like it, but it seems that the air dam is designed not for aerodynamic purposes (like the 140mph speedo!) but as a cosmetic cover for this "Orifice". What I need is a workshop manual, or a good Vauxhall mechanic.
Unless your planning to go off road which is not what the Antara is designed for the air splitter/dam shouldn't be a problem. In 18 months even in snow it has never hit anything or got stuck. It looks better with it on.