Honestly, for the very minimal gain you'd see (5-10hp, if any), I wouldn't chase this path with a $200-500 tuner that requires months to learn. The 3.1 version of the GP is best used as a fairly good mpg driver, and that will be negatively affected as you add much more than 1-2 items for minimal gains at hundreds of dollars each.
There's a good UNYCGP crew I used to meet with in the WNY region, and Mike "mguzzo" here is one of the main members up there, if you want to see who is available with a tuner in the area to try.
