I use Sunoco Ultra 93 and Gulf premium 93 octane. The difference in 93 versus 87 octane in my area is 20 cents a gallon. For a lousy $2-$3 more a fillup I'll stick with the premium gas for premium performance. My mpg's are great so I'm not worried about paying a bit more. My XFire now has just over 9000 miles on the clock.

Bob