@sam's comment about his mate wanting to "drive fast"...... Why? I'm 17 and I've done 17 hours in Official driving lessons, and quite a few more on private tuition. I'm a fairly confident driver, and yes I've made a few mistakes in my lessons... However, I don't see the reason for kids my age sticking body kits on their cars or messing about with the engine when all they do is look crap and sound crap. Not only that, do they tell the insurance companies about any changes to the car? Probably not, or their premiums might go up. And if they don't then their insurance is void (but don't quote me on that)... Have an accident and you're screwed.
Now I'm happy doing the speed limit, hell I only usually do 50-55mph in a National Zone, partly down to my experience, and partly down to my confidence. I'm not driving because I want to drive fast, like most of my peers, but I enjoy just enjoy the sheer pleasure in Driving, my ability to enjoy myself driving down the road yet NOT speeding or looking like a twat. I'm happier doing 40-50mph on a back road, than showing off in the highstreet blaring tasteless music through subs more suited in a club.
Sorry for harping on, just my rare 2 pennies worth.