And just a heads up, some folks have done dyno tests on 2011+ Mustang "V6's" with 87 vs 93 octane.
Even with the stock ECU & tune, it gained 7whp. ECU's CAN advance timing to an EXTENT, and will generally take advantage of the increase in octane. Yes, these engines (well, the tune) was designed with 87 in mind - specifically because of the fact that there would be a massive uproar if your run of the mill Focus needed premium, but they tuned them EXTREMELY conservatively to get by with this low of octane on a high comp. motor. It's always a compromise, no matter what tech (Di vs. Fi, TiVCT, etc).
When aftermarket tuners crack these and start making GOOD 93octane tunes, I can forsee a 20whp+ boost in power on an otherwise stock car.