from a technical stand point, your milage should improve, because part of tuning is to lean out the fuel injection to make more power. so assuming you can keep your foot off the little peddle on the right, you should get an improvement.
James is not the only person making custom tunes, any shop with a dyno can do one for you, and bamachips from explorerexpress can as well. i chose james for two reasons, in my town, there is only one dyno, and the guy wants a fortune to tune rides. and two, he has AMAZING Customer service, he has made me no less than 6 tunes over the last year with out questions asked, and was more than willing to assist me if i had any problems.