Later in the manga Itachi might had a chance of beating Minato with all his master in genjutsu and stuffs but Since Minato have KCM.. Itachi not even a chance. Mmwwaaahahahaa!!
minato has the chakra of kurama in him but no the beast itself (meaning no bijuudama) regardless, minato still wipes the floor with itachi. He doesn't need kcm to beat him, but with that up...He is the fastest person in the narutoverse.
Even tobimaru admitted that minato was faster/better without kcm
Apparently Minato basically has an upgraded form from what the Silver and Gold brothers had. Still, that makes him even more powerful.
And it would make sense...I mean, wasn't anyone surprised that Naruto's BM looked more like Minato's cloak rather than Naruto's jumpsuit?
I thought it was odd that the BM cloak took on that nature...I would have thought that the natural progression would have been an even cooler looking jumpsuit.