Tiff you speed demon.. don't buy a radar just use your boobies..
I've wanted a radar detector, but decided they were more trouble than they're worth, like James said, cops give people a difficult time when they see that you have one in the car. It will definitely get you a speeding ticket if you're stopped, where a warning could have been a result if you didn't have one.
Mostly in high congestion zones you will find your Cops... so go with the flow of traffic in those areas... (That's probably every area in NY ) I know when I visited NY a while ago the traffic was crawling... and that just gives me road rage really.. I like going fast. I live in Ky though and Cops are few and far between so I can get away with speeding really easy and can usually see Cops well before they see me coming so I have time to slow down. And of course knowing the traffic court people helps.. (Small towns do have their plus sides)