I have the 904 big bore kit with a ported/polished head and 1mm oversized valves, and my hp went from 54 to 70 and torque went from low 40s to mid 50s. I am waiting to get my bored out stock carbs delivered, that should add about 5-7hp, and finally I will be getting reground cams to put me up near or over 80rwhp, and I'm hoping to be in the 60 ft lb or better range for torque. Power is money, how much do you want to have and how much do you want to spend? There are many many guys here with the big bore kit, and I don't know of any reliability problems. These motors are pretty much bullet proof. These bikes run much better stock than the numbers suggest, I was very happy with mine in stock form, but I just like to have more power.
