Why waste your money on Radar Detectors and all that crap?
GO THE SPEED LIMIT.
It really isn't that hard, think of it this way: it saves wear and tear on your gas pedal, brake pedal and brake pads from when your constantly slaming on em to avoid Mrs. Daisy.
I've seen friends get brand new (insert name of excessively large engines American "Sports Car" here) the next day they get a Radar detector thinking their car is uber fast. At lunch time as I'm coming back I see em by the side of the road getting their ticket from the local Cop thats assigned to the High School that month. Their little plan to speed back to school to save time made them late in most cases.
All while I chug by in my faithful Diesel Sedan.