How about an even better Idea....I use something which didn't cost hundreds of pooooonds...it works every time and its legal......
Yep, I keep to the speed limit.
If you were to keep to the speed limit there would be no need for jammers, entrapment devices or the like...in fact, if everyone kept to the speed limit there would be no need for speed cameras.
So, top tip... keep inside the speed limit. It saves money AND it saves lifes.