Just to throw it out there, I took out my K&N CAI and did the Gotts mod in my 08 4.6L. I took it off because I couldn't stand the drone anymore, it was driving me crazy.
I feel a much bigger difference in performance with the Gotts than I did with any of my custom tunes and K&N. I'm also getting at least .5mpg better also. I reset my Gryphon and am currently running the canned tow tune. My truck has better power now than it did with my custom 93 perf tune.
Now I'm waiting for my 87 perf tune to be rewritten, time to wait again. lol The Gotts mod was the best and cheapest thing I have done to my truck. Too bad I didn't know about it before I had bought my CAI.