I had an 01 with almost the exact same setup. you should definitely get some custom tuning, it will not only help any possible lean conditions caused by the CAI, it will take advantage of the CAI and the Exhaust to get you better possible gas mileage... I say possible mileage because I noticed that mine went down as well, but I am pretty heavy footed so whatever gains I got I used, which used more gas... after a few months of me being used to the tunes and me relaxing my throttle use I got better gas mileage. I notice it most when I am doing a lot of highway driving. The other benefit of the custom tunes is the tow tune will help pull your boat and car trailer better. plus Bill tunes them to you and your style of driving, plus where you live.
Hope that answered your questions
, feel free to ask more though