From my understanding/reading it seems as though without a tune you won't see much of a difference in performance running the 93 octane. One of the other members said that he was still seeing a decent amount of knock retard even running the 93 octane. I've viewed a few different forums addressing this issue as well as I was looking for ways to boost power without going heavy on mods and many have them have stated they aren't seeing really any performance boosts from running 93 octane in the 3.6 lfx vvt. The ones that say they do don't really have anything other than anecdotal testimony to support their claims. Does the knock sensor advance timing very slowly? Or should it have things figured out after a tank of premium goes through it? Is their anything else in the sensor/engine system that might prevent the motor from taking advantage of the higher octane?Getting better MPG is not the main purpose of Higher Octane Fuel or Advancing the Timing, it is getting more power, although there can be a rise in MPG depending on how you drive it.I've tried the higher octane in my 14 LTZ 3.6. If I'm climbing mountains and fighting the wind I see a slightly better gas milage after a tank or two. But no where near enogh to justify 20-30 cent a gallon price increase. I get up to 34mpg @ 75 using 87 octane top tier gas. Now paying just a few more cents per gallon for that is justifiable in my humble opinion.