I just installed the +6 tune with after filling up with 93. I plan on reflashing to the +3 tune for the winter; should I continue to run premium, or would it make any difference? I ran 89 before reflashing. My Civic is stock otherwise.
Hondata has said in the past you can run that tune on 89, just don't expect the advertised power. Also consider incorporating "Hondata Mode" where you have a dual tune setup. Econ button on is stock. Econ button off is + 3 psi.