I do think I want to possibly do something about the fact that cops are encouraged to use shitty cop cars while all criminals have an Infernus etc.
However, I don't want all cops driving around in black Infernuses also...
It's hard to balance fairness and 'realism' in this. Perhaps the way to go is to make cops pay to spawn pursuit vehicles? Or allow them to pay a huge sum to convert a personal vehicle into a pursuit vehicle? I don't know. Those will still lead to every cop on the server running around in a sports car, which I don't want to see..
As for the original suggestion of the police heli, I don't see a reason why it shouldn't be requestable, but maybe for a fee.