I bought my car used with a K40 jammer installed. The guy that sold me the car said it cost 2k.
I am/was a cheap person. But, I usually believe that you get what you pay for. I have owned a cheap radar detector in the past and it did not work early enough. All it did was tell me "Hey, you just got caught speeding, so you can pull over now." It's like adding insult to injury. It never did anything other than that.
This jammer gives you a few seconds to slow down by essentially blocking the first attempt by the laser gun to check your speed. Also, it detects radar signals early, aimed at other cars from very far away. This gives a few seconds to slow down before within eye shot. The audible voice will say if the radar signal is from the front or rear. When a signal is detected, blue lights flash from the steering column to alert, very hard to miss and you can put the volume on mute to just see the blue lights with no voice. Everything is very well hidden. The only thing you could find would be the 4 inch box in the driver's side door compartment on the bottom that tilts out like 45 degrees.
I drive pretty fast and I don't have a ticket in 9 months of owning an M3. It's slowed me down about 30-40 times. I don't believe that it has ever been wrong. The only thing I worry about is motorcycles with no radar signal.
Stress is a killer. I have peace of mind and it's worth the money if you have it.
Last edited by AshyLarryMP; 02-27-2013 at 08:10 AM.