Hi there!
I didn't know if this has been registered already, but I think that the boost / nitro in its current implementation / setup pulls excessively much.
You only need to press the nitro / boost key only once a second and only for a single frame (e.g. a pretty damn short time) to keep your kart at full speed. You do not consume much of the boost gauge (if done well you don't even see it decrease sometimes), and it makes it possible to race mostly all tracks completely in full, boosted speed.
That's unfair to players who don't know this and makes the A.I. look pretty dumb.
I would recommend to tweak it in a way so that the short key presses do not accelerate that much, and that you have to keep it at least 1 second or so pressed to get a real noticable acceleration.
What do you think?
PS: What's with the weird bumping when hitting cars / walls in 0.8.0? I hope someone wrote that down already.