Well.. Octane boosters.. Honda manual clearly says NO FUEL with MMT additives. All these so called boosters have MMT, magnesium based.. some even have lead.. over time you will see O2 sensors bye bye.. premature spark plugs damage and you will even see deposits on spark plugs even after single use.. add replacement of fuel filter prematurely. If you think you will add booster to increase octane and it will be good.. then you are mistaken.. it will start ruining your engine over time and if you use it regularly.. Wait for the Check Engine light. It will lit soon.
Also there is another big misconception. If octane booster says add this bottle and it will increase 5 or 7 points.. it's not making 87 become 92 or 94.. it increase point which is 0.5 or 0.7, so it will be 87.5 or 87.7..
OK Toyota,manual says 91 and didn't hurt sir @autophile car. But with due respect you will follow @autophile as per his experience or follow what Honda will tell you when you pick you keys to your new car.. As I said earlier cars are investment in Pakistan, people start thinking about resale before even buying , how come you will no follow what Honda tells you?
Refineries add hydrocarbons at molecular level to increase octane number. Yes Octane booster works a little but it comes with surprises and you cannot add it regularly.. your car engine is not like two stroke that you add engine oil to it. Also how you will claim warranty if you start hearing a different sound from engine or malfunction light in your cluster. A dealer will easily tell you.. you used a below rated fuel.
I have driven and driving turbo cars since 2003.. and I can tell you that using boosters will hurt you if you start using it regularly.