Well, realize that if you do these mods individually, you're going to need a retune after each mod. If you can afford to have a little downtime, the best thing to do would be to have your tuner tune for all the mods and install them at the same time. The E-fans and gears require a retune. The LT's can go without a tune but really won't shine without one. I used to live in Wabash, IN. I can't recall you having access to 93 octane. 91 will do just fine. But yes, it will be a difference.