I've had an M27 installed in my lower grille (yellow) for some time. Had it tested by DJRams80 and his PL2 a while back, and it was JTG all day. Just had it retested with DJs TruSpeed and sure enough, he got PT at 240-260 ft on the passenger headlight . Driver headlight and center mass shots were JTG.
Some recommendations were to move into the upper grille (blue), move outward to the red to better protect the headlights, and veil. The heads are currently mounted in the yellow spots.
I'm still debating on what course of action to take. The blue would be ideal, but the grille moves with the hood, so I'd have to be extra careful with the heads when closing the hood. Also, clearance between the upper grille and the radiator is an issue.
Anyhow, just another data point for you guys considering the lower grille install.
PS - Checked the heads with my cell phone camera in parking sensor mode last night. All LEDs appeared to be firing.