I think you are comparing the non turbo VQ's with the stronger VQ30det/VQ25det. Nissan always run stronger internals in their turbo motors, and the VQ35 rods are lighter afaik to raise the rev limit. Perhaps do a little research on the subject. The HR rods are a little stronger apparently.
The figures you posted are approximates, and for a manual rwd car. It should be close if you can get some good fuel into it, like they run in Japan. Auto cars will lose around 30kw and awd will be lower again. My stock VQ25det would be running over 400kw if it was rwd and manual box. No extra outlay for me.