Quote Originally Posted by February
You might say that the entire Naruto's huge beam / big crater is kind of over-doing it but you really have to imagine how powerful a miniture Kyuubi would be like, and it makes it more realistic for him to be that strong. After all, Kyuubi is not a ninja in the first place so it shouldn't have normal attacks.
I think there's more of Naruto in that miniature Kyuubi than you guys think. The giant chakra attack was essentially hundreds of red and blue Rasengans compressed into a black super Rasengan. Even though it's all Kyuubi's chakra (and so his "power"), I don't think the Kyuubi could have done a move like that without Naruto.