Bumper cover removal?

It helps to use two small screwdrivers, gently prying at opposite sides of the clip. Take your time as they are easy to break, and remember that they are considered single-use fasteners. It's a very good idea to have a bunch of spares on hand because you WILL break at least a few. Note that there are several different types used, the dealer parts department will have all the info. Also I'd suggest doing some research before you install a CAI. On the WRX and STi they are of little benefit and can actually be detrimental because they affect the airflow through the MAF sensor which is calibrated for the stock intake setup. Some brands of intake are worse than others.