Removing this will increase your airflow at full throttle and boost HP. I did this to my truck and could tell a difference in high-speed power. It is important to know that cutting this plate could void the warranty on new trucks. To remove this plate unbolt and completely remove the TB from the truck. This is done to reduce the risk of objects falling into your intake. 

Once the TB is removed it can be cleaned. After it has been cleaned the plate can be removed. Looking at the bottom of the TB you will be able to see that the deflector is connected to a thin plate that is fastened to your TB butterfly plate. You will also notice that the idle hole in the thin plate is smaller than the idle hole in the TB plate. This is so because the throttle body’s used on 4.3s are also used on other vehicles. The hole is drilled in the thin plate to match the vehicle on which it is installed. 

Loosen the screws in the middle of the throttle body plate and remove them. Turn the TB to full throttle and gently remove the plate from the brace. 

Cut the half moon shaped deflector off the thin plate. Do not cut any other parts of the TB. 

Grind the edges of the thin plate smooth and slide it back into the bracket. 

Tighten the screws back down, clean it, and reinstall the TB on the intake. After we did this mod we was surprised at the increase of HP at med and high speeds. We have done this mod on numerous trucks with all the same results. More med and top end power at full throttle.