I'm watching a video on the Atomic right now and see some things that I'd change:
1) I see the same issue with this boat as I did with the other, the drive shaft is too tight.
2) Did the 2S battery come with it or did you have to buy them? The video I saw showed a 3S 11.2volt pack. A 3S will be faster than a 2S
3) That plastic prop has got to go. Plastic props tend to flex under load and will break. I know of someone that can sell you a sharpened, polished and balanced replacement that will outperform that plastic one though, unfortunately, it won't be real cheap and, if you get your finger in the way, it could take it off
I was doing a bit of research and found this is, more or less, a toy grade boat. I'm assuming the same with the Valvryn. These are not really set up or made for going real fast. I did see a review video on this boat, which showed an issue with the test boat as well, the link being below. let me know if any of this is what you were seeing.