Wonder if we lose about the same on 87 octane.
http://www.autoblog.com/2015/01/05/2015-ford-mustang-ecoboost-loses-big-power-on-87-octane/
According to this document, the 2.3-liter EcoBoost makes 275 horsepower and 300 pound-feet of torque when running on lower octane fuel. That's a substantial reduction of about 11.3 percent compared to when the engine drinks 93 octane. Interestingly, according to Mustang 6G, that finding was a bit better than expected, because a Ford engineer reportedly said power would be down about 13 percent without altering peak torque.