I installed my Injen CAI
The piece you have to cut is shaped almost like a triangle...don't start at the top and cut the WHOLE "TRIANGLE LOOKING PIECE" OFF.start in the middle or towards the bottom. (By the way, To see what I mean by the "triangle" you have to take the bumper off.) Cut a circle about 4 or 5 inches in diameter.
But take your time, mark it before you cut it if it helps, I used the inside of a roll of ducktape as a measuring device.
The pipe that connects the ECM to the bottom of the cooling fan, you know the one you have to cut. don't cut as much out as the directions tell you to, mine was too short and I had to get a new one.
sorry for rambling, hope this helps
Its worth it, the Intake