I did the 103 kit with the 255 cams and I was a bit disappointed in the gains.
I will most certainly be doing some head work soon, in order to take advantage of the extra displacement. So far, four of my buddies have done the 103 kits, all with cams, however only two of these build had the S.E heads put on. The heads made a significant difference in performance. MUCH MORE torque!!!
My suggestion would be to replace the cams and have the heads worked on by a reputable craftsman. You will find that the cams and head work are the two biggest components in waking up that motor. Remember to choose a cam that suits your riding style.