There has been several opinions on how much and where youget more power...
I noticed a distinct "seat of the pants" difference over the straight Gen 1 setup, especially over 5K the bike really wakes up...
They say anywhere between 4-8 HP, I have seen posts of nearly 10 more but that is probably stretching it. I have rejeted, full M4, cam swap, and can tell a MAJOR power increase over stock. Considering a new set of 2nd gen Intake cams will run you about $200 compared to custom cams of atleast 3x that much...it is a good place to start.