Must be a Midwest thing. 87 and 91 octane are always 20c apart here. Even at 27% difference, there is no octane booster in a bottle that is cheaper than premium.

I'm in the middle of a long trip and I tried a couple of tanks of 87 octane. Fuel economy is exactly the same but top end power is gone. It's like driving a 240 instead of a 320.

__________________
CENSORED due to not family friendly words