Currently I have a little under half tank of 89 if I fill it with 93 with the 93 tune will I do any harm to my car or is it just not going to be as "powerful" because it's half 89 and 93. Sorry for dumb question lol
I take it you have not loaded up the 93 tune yet? If that is the case I would just go out and do some hard pulls to burn through that 89. If you already loaded the tune then I would add in the 93. It will just be difficult to move your OAR up since the gas is diluted with a lower grade gasoline.
As far as it hurting your car I don't believe it will, but I would wait for another response to that.