Yeah, I would say 4 hours is very realistic, if you are cautious with wrapping possible rubbing areas, and want to insure everything is tight and fits right. There are multiple ways to have the filters sit in there, and you will only figure this out once you do it - you can either have them behind these two screws (one is used to mount the horn), or move the filter further down the lower tube and mount them next to them. I looked at various install pictures, and decided to mount the filter under/behind the screws, making them pretty stable (plus I did not like how the filter sat on the lower tube if you moved it down the tube). Today, I finally got to drive the car, and the butt dyno feels great. If I were to do this again, I would protect the lower tubes with blue tape, as you put them in and out of the holes, to insure a good proper fit, and then once they are installed and tightened, take the tape off. I put those in and out probably 3-4 times, and by the end of the exercise, I had various scratches on the surface. Something I would also do is when you put the bumper back on, make sure you have it in the right place underneath, before any screws/pins are back in. I put the top push pins back in, and then when I went underneath to put the screws in, I noticed that the lower part of the bumper was on the wrong side of the lower plastic cover, and had to take out all of the pushpins again to re-align. Overall, it was still relatively easy, but after installing probably 6 CAIs in my life, this one was by far the hardest. Good luck to those installing it - it is probably the best.
As for Kyle, here is his info:
Nissan 370Z Forum - View Profile: Kyle(Houston), and he had a price that no-one could touch.