Well, for me at least. I had the noisy startup rattle (which I figured was the loose tensioner everybody else was talking about) and my check engine light would come and go. I also had another weird resonating rattle under load in fifth gear, which I had attributed to a skid plate I installed.
I have a GanzFlow and Amsoil, so I went in to replace the stock intake doodads to go to the shop for CE, and when I looked at the airbox, I saw that it had popped loose on the bottom, but the top clasps were still hooked.
I had to wrestle with it some to get it all back in place, but the startup rattle is gone along with the cchekc engine light.
So if you hav those two problems, you might want to take a look at your airbox - it isn't readily apparent just looking at it from up top.