Soooo... After days, after visit BMW service center and after they tell me a price to put this one (something about $1.5k), i decide to put it myself. Pay $150 - OK, but not $1500... :X
I tried to remove bumper - no space to place it (how difficult to do it with headlight wash.... :X)
I tried to remove grille - fit, but no metal support there.
I think about right-side of car (there a airbox on "i" BMW's are) - but again no metal support there.
So, I put off a cone on this megafone and tried again to find a place to it, and got it! At left side of motor-space, in metal support of brake liquid (did not sure what is it) it fits millimeter to millimeter!
I drill 2x6mm holes and fix mounting bracket on it. When put a speaker head, then a resonator. So, a distance between this box of brake liquid and speaker resonator something about 1mm
Then I use a standard stereo cable to do wiring from speaker to trunk where placed a amplifier for this `alarm`. Cable pass over passanger door into the interior of car.
At final i tried to horn one time only to check it (night...), works...
Some days more I will put link to some video...
[sorry for my english]