2010 Charger SXT 87 Octane Fuel

[bfenty]

I apologize in advance if this is a stupid question.

Is there a tune available for 87 Octane fuel? The lowest I have on my i1000 is 89 Octane-but I would like to run with the lower octane fuel for cost reasons. I ran the 89 Octane canned tune, but I'm getting knock in the 3K-4K range, as well as the car seems to have a bit of a shimmy to it while I'm driving which isn't there with the stock tune. I'm going back to stock for now to be safe, which is a shame because I really did notice the car feeling better with the tune...maybe just a placebo effect, I'm not sure.