While doing my 9500ci installation I noticed that the "nose" of my C6 is shaped somewhat like a beak: the bottom surface slopes downward from the sides in a very slight V shape, and the front surface is curved outward. I took a few measurements, dusted off my high school trigonometry, and calculated that the slope of the nose is ~1.59 degrees. Thus, if I just slap the heads to the underside of the nose using mounting tape they will be tilted by ~1.59 degrees.
I know the Escort spec is +/- 2.5 degrees, and ISTR that Radar Roy did some testing of ZR4s and determined that an even narrower range was optimal. What Would You Do?