Yeah, I'm always paranoid about my valve train too, it sounds just like that, but mine was just completely redone, so it's normal (atleast I hope so, or else I'm in trouble) .
Haha, yeah, freaks me out.
I did let it run for about 5 minutes tonight before i took it out just down the road for a few minutes. When i got out of the neighborhood i tried to slowly roll up second gear, sputtered/rev limiter feel even on a slow roll a couple times. Slowed down, tried again, smooth. Got on her hard and it never sputtered again.
So, i dont know, i bought this bike 4 weeks ago roughly, had it shipped here from a couple states over, rode it twice for ~5 minutes because its the wrong season to ride here. Didnt have any stutter issues, but seemed a little weak. Figured i might as well jet it while i have it tore down for the plating electronics and what not.
Good god the power surprised me, this/these things have some balls. Last bike i owned was an 05 R6 i bought new, maybe im forgetting the power of that, its been a few years, just really amazed at how hard this thing pulls.