I will be installing 4 Inceiling M3s soon (once I paint them) and from what I can tell the only thing below the drywall is the trim ring and mesh screen.

M80s VP180 4xM22ow 4xM3ic EP600 2xEP350
AnthemAVM60 Outlaw7700 EmoA500 Epson5040UB FluanceRT85