Well I hate to say it but if you buy the tuner, you fuel milage may go down. The reason for this is Bills tunes are great and it is hard to keep your foot out of it.....
On another note on there web site it shows you can save fuel with his tunes 1-3 mpg. If you but one you will not be sorry. Also there is a post on the forums about CAI. I would do the home built version, you will save a few hundred dollars and get the same performance, and with the extra money you can buy the Gryphon and the exhaust.