@1:31: As in the other video with the KPV, the gap that opens up on the start cannot happen. My suggestion is to apply at least half throttle once you are gridded up and approaching the green, so as the kart in front of you goes, you go.
@2:58: I was going to be critical of your cautious start, but at this point I see why! That was pretty crazy, nice work weaving through there.
@3:37: Similar to the KPV video, it looks like you are being quite gradual on the brakes, and then the kart washes out in the center of the corner.
General comments: The kart looks like it has decent speed through the high speed corners. It really looks like you simply aren’t getting the kart slowed down enough for the more technical sections, as you miss the apex relatively consistently, and the kart will ‘wash out’ from under you in the center of the corner. The fact that you gain on others going in, and then lose that gap as you exit the corner is another classic sign of this.
Not having run newcastle before, I’m sure someone else could give you some better tips on the driving. The braking is still somewhat of an issue.
The kart does appear to hop in the cell-tower corner, but looking at the undulations in the rubber, I suspect that other people are having the same problem.
Where was your front and rear ride height set?