I don't think that's the cause of the high LTFT's. I had pretty much the same as Dale when I had the Cobb SRI. 10.2 at idle and 14.8 accelerating. I put the factory airbox back on and they dropped to -3.9 and -0.8. I swapped them back and forth a couple times to make sure I hadn't left something loose and got the same results. With the Nano they are +4.7 and +7.0. It's something to do with the Cobb for sure. Isn't that about what you are getting with your Nano also?