Ok, I called the dealership which did the work and asked them what I should expect of mpg, they said a drop of 4 to 5, but then a bit later the guy said one guy they no didn't experience a drop at all, still getting around 42. I did find out they didn't rejet, they shimmed the needle and adjusted the "air screw?" I think thats what he called it, well to adjust the mixture I guess. He told me to run some of that ring frre that Yamaha sells and see what that does. I did expect some of a drop and yes realize that at first I would be hard on the throttle, but this past weekend did baby it and it still seemed to be less then what they said I should expect. I love the pipes and the sound, but when going long distances it just doesn't pay, at least strating to think it doesn't.
By the way, I do notice that the throttle response is much greater.
As for the terrain, it was mostly flat county roads.