You disconnect the negative terminal for like 30 mins to let it discharge and then reconnect it and drive. Let's the ECU relearn how to fuel the car after you install mods.
Had a custom tuned Si and was seeing 40+ on the highway at 70-80. Either you want to do a trim relearn or flash back to stock and see if your mpg comes back. Are you only running the tune or do you have mods as well?
A lot of states don't have 93 anymore. AZ used to have it but it never came back one year and has been only 91 for the last 20+ years. Don't know why 89 even exists at this point.
I didn't have a 10th Si but 2 10th Sport hatches. I love the fact there is so much more space under the hood to work on stuff compared to the 10th and the body lines are not as jagged.