The restriction may not really be there.
When you look at the opening to the air intake you see the black plastic that covers most of the opening of the air filter and you think it's restricting the air flow into the filter and thus the engine. You think by removing it or cutting part of it away that you'll be opening up the airflow.
That may not be the case and I'd think twice before doing it. By constricting the opening, the engineers have created a venturi effect. The example I'll give is your garden hose nozzle. If you had a no nozzle, and just let the water out you would only get the flow of the water coming of the hose. The water wouldn't go far or have much pressure.
Now add a nozzle. Start with one that has a variable outlet. As you constrict the flow, the water comes out faster and with more force than with no nozzle. The constriction causes pressure which accelerates the flow of the water. In the car, the air is now being accelerated into the air filter and thus into the engine.
So if the Chevy engineers knew what they where doing, which I think they do, they purposely designed the opening for the best air flow given the cars conditions. You might see some better performance with a non-restrictive opening at very high velocities. But probably a speeds you'll never drive at.
So unless the Chevy engineers say otherwise I would leave well enough alone.
Just my thoughts
Carl
