Typhoon The DiabloSport i3 came with preloaded tunes and one is specifically for gas mileage. But I bought custom tunes from Hemifever (engine and transmission tunes) specifically for 91+ octane (they will do whatever you want, pretty much). Hemifever does a great job too. They will take your data from your logged test runs and analyze it for you and send back a file with further tweaked custom tunes. Also, DiabloSport does a great job working with you in case the PCM gets flashed by a dealership or shop when they do service (I bought the PCM from DiabloSport as well). Total cost for everything I listed previously with labor, including a 180 degree thermostat, was just shy of $6k.