Okay, so thats 15-20 with the tuner? and I am actua;;y planning on getting 3.73 gears/7.5 t lock, 18" chrome saleen rims, and 275/35-18 tires. So basically i'll be upgrading my tire size and gears. I know it holds 3 tunes. So ive herd i could go like 93 octane performance, 87 octane economy and 91 octane performance?