I installed my Ingen CAI on my 08 KC Pro-4x this morning. Everything was pretty simple and just as the directions indicate. The only thing I did that was a little different was I removed the rubber grommet from the front stud that holds the OEM CAI down, and stacked it on the middle stud. After I installed the Injen I noticed that if I shook the CAI a little it was tapping on the stud. With the second grommet on the stud it is pretty tight with almost no movement.
I put over 100 miles on my truck today after the install and I am very happy so far.
Yes it has a little more noise than stock, but not much. Running around town I can turn my stereo volume to 4 or 5 (which is pretty low) and I can not hear the CAI over the music. On the interstate it is audible if you get on it to pass. Cruising at 80 I could hardly tell any difference. Punch it at 60 and you can definitely hear the difference over the stock unit.
I was worried the CAI might be too loud after hearing some of the other brands, but it is not. No whistling sounds or other high pitched air noises like some of the others. The sound when you put your foot in it is actually a deep tone.
My JBA will be going on soon, but I wanted to run the truck with just the Injen CAI to get feel for it before I did the exhaust. The Injen was pricey, but I like the fit and finish (top notch) and it is worth it to not have to listen to a whistling CAI going down the road. :cheers: