I took some pics of the R34... I think what you're seeing with the back jacked up is because for some reason where it is bolted to the base in the back, they put spacers on the back portion... so the back tires are farther away from the base in the air than the front tires. I tried to take pics with a post-it note marking the tires off to show the difference:
Back wheel:
Same mark on the front wheel you can see the difference (front wheel is lower):
Out of the box I think it sits pretty flat? You can really see the colour difference on the bumpers here though -- it's more pronounced than in person, but definitely noticeable!
