i use personal sences as defence #1, then use a detector as plan #2. I got a whistler, I only use it on the hiway because it is too annoying in the city. (false alarms 90% of the time).
cops are too smart, they lazer your car at the last possible moment, so even if you do jam your breaks its too late, and you already got a ticket.
as for the scramblers i can see how they would save you if there were a bunch of cars goign in the same direction, however if your the only one you will get jacked instantaniously!