I read that in one of the Mustang magazines. They got a really small gain. I think the other poster was right about 3 - 4 horsepower, maybe. That's too small to even notice, maybe 1 or 2% over stock.

As far as gas mileage goes. 93 octane is 30 cents more per gallon here than 87 octane or about 10% more. There is no way 93 octane on a stock tune is going to give you 10% better fuel economy. Driving differently, though, could easily save you that amount.

 

funny I average 20.5 mpg no matter what octane/tuning I use. Cant see how you can get 100 mile per tank extra by raising the octane. thats unless your driving down hill the hole time.

 

93 is usually a better quality gas and many people are having knock problems with the lower octane in the summer heat...I have always put 91-94 in, tried 89 once and the car didnt exaclty like it and I got crap for milage...could have been bad gas but never had that problem with higher octane.