I installed the TRD CAI on my truck a few months ago, here's what happened.
I ordered the intake from TRDparts4u. It went in with no problems. The directions were very easy to understand and the whole thing took about 1 hour. Everthing fit perfectly and it looks like a factory installed part. This airbox uses the same hole in the fender well to pull in cold air from outside the engine compartment. When I started the truck it seemed to rev up slightly smoother and quicker. Next I went for a drive and immediately noticed the growl/howl coming from the engine compartment that gets progressivley louder as you accelerate. My "butt dyno" says she pulls harder especially in the upper RPM range. It pulls strong all the way to redline where before it seemed to run out of steam on the top end. I find myself putting my foot down more just to hear the nice howl of this intake. I am very happy with it.