i doubt he will be stronger than kakashi when he gets it, even though that new jutsu MAY be more powerful, it does not mean naruto can just win over kakashi!
Naruto will prolly have a more powerful jutsu than kakashi, but not then suddenly better than kakashi in battle.
He WILL be stronger than Kakashi. If your doubting it cause Kakashi is a fav, then do me a favor and just shut up. Give some proof before you doubt something that is most likely gonna happen.
Btw, didnt Kakashi say something about combining Lighting Element with Rasengan? I might have had the wrong translation or something.