if your close enough or he's specifically guning for you... your screwed. radar travels faster than you could ever react to the detector going off... like it would matter anyways. they do however, give a warning buffer of up an coming radar signals. but the majority of cops won't gun constantly. they pick an choose. so basically he might be sitting just waiting, and your detector isn't picking up anything, he sees you... guns you... an its all over. he's got your speed before you ever had a chance to slow down. laser is the worse, I got nailed with that like 5 years ago.... only car on the road, mine went off... seen him sitting 1/4 mile down the road...sure s**t enough he nailed my speed that far away with it. 93 in a 65 zone = Ouch
just don't speed period, its the best detector you can't get. whether you speed or not you'll get there either way. most times speeding doesn't really get you there any faster. example... I travel 80 miles to pick up my boy, 30 miles into it someone will pass me doing like 80. I get to my destination and guess what...there he is stuck in front of me at a stop light.
soooo point being don't get one..dont speed..if you have to be somewhere leave earlier