As others have said it just depends. Regardless of whether the policeman is a power hungry bellend or not (you get good uns and bad uns like you do in every walk of life), there are more driving laws than speed limits. I'm pretty sure spinning your wheels is against the law as it is not being in control of the vehicle or something, you get dangerous driving, driving without due care and attention etc etc. It would depend on circumstances, I doubt booting it past a school would go down too well even if you only boot it to 30 but that is a pretty retarded thing to be doing in the first place.
There's a time and a place, in front of a police car isn't either of those, doesn't matter if you aren't technically breaking any laws, just opens up a can of worms. A policeman is just as capable of thinking "what a ****" as you or I but the difference is he has the authority to do something about it.