try with a longer xrt some hits on someones back and watch where it hits it, the same point as the original car or the moded car, so if you have a longer nose you can go into(!) the car or you just hit the bumper? i hope you understand what i wanted to told you
the problem is with that thing is, if i saw well on some videos the coordinate of the car is changed, so there will be some crashes in multiplayer mode if you have e.g. a longer xrt based vod file then the other racers, don't know what happens but i don't think it will be good
not the same as nos in real life, because nos is limited by it's tank, and you can use only that amount, but in games it's recharging like the kers in the real life, but kers is limited by the rules(or how you can use it), so it's nearly the same thing, those give you more power and thats all