Is it still legal? Define "legal." Will it follow the strictest letter of the law? No, probably not. Will you be living up to the general spirit of the law? Yes, since that law was probably written before the era of 50cc 40mph scooters. So long as you obey traffic laws and don't act like an idiot, you should be able to get away with it. (I say this based solely on my experience in Kansas, where "motorized bicycles" are not supposed to be able to go over 30, yet all the Honda Metropolitans are registered as "motorized bicycles" and those things definitely go over 30mph). Either way, so long as law enforcement doesn't clock you going over 30mph, you should be fine. Of course, you could always argue that it's safer to speed and keep up with traffic than impede it by going slower. I don't know if that'd work, but maybe you get bonus points for trying? :)