[freshwhite335]

Technically the best place for them on the M3 is at the top of the lower portion of the bumper. But if that location has worked for you in the past then stick with it. It's much more attractive.

EDIT:
Also check out a product called VEIL. It's a liquid coating that goes on your headlights that reduces the effectiveness of jammers. Most of the time a cop will aim their laser at your headlights or tail lights.