Do the Dodge Chargers absolutely require 89 Octane Gas to run properly?

If dodge is reccomending 89 its for a reason, most likely the engine will have a spark knock if you run 87 in it. now being a new computer controled car if run 87 no damage should happen because the pcm will detune the engine to prevent the spark knock. now when the pcm detunes, the performance will be gone also, now the exstent of detuning i dont know? but i would stick with the 89 or higher thats reccomended