Octane 86 with an 87 performance tune??

[chito]

Hello,

i have a 2004 FX4 and had purchased a gryphon back in 2009 with an 87 performance tune due to the fact that i had installed 35" tires and put a leveling kit on it. The problem is, i used to live in New Mexico where the gasoline octane grade is 87 (regular), BUT, in 2010 i moved to el paso where there is no octane grade 87, only grade 86 for regular gas....

since 2010, i have been using grade 86 on my 87 performance tune, i havent had any problems, but should i order a new performance tune for the grade 86? is there even a performance tune for gasoline grade 86? or should i just leave it the way it is?? should i start using mid-grade 88?

My last question, i have 35" tires, and i was thinking of regearing from the stock 3.73 to 4.56. Can i keep the 87 performance tune i have on it now if i switch to the 4.56 gears, or would i have to get a new performance tune?

Your help is appreciated, thank you