If you want to really jazz up the quality of your gasoline for a high performance engine, the best additive is MMT which may not be listed on the label but one product I'm pretty sure has it is 104+ Octane Boost. Not cheap but it really works.
MMT is a manganese-containing compound - methylcyclopentadienyl manganese tricarbonyl - which works as a lube for the valves and piston rings as well as boosting the octane.
Used to be - when leaded gas was the norm - the tetraethyl lead was dosed in together with MMT, which gave it a synergistic effect. But even without lead, MMT is still great for the gas engine... the best additive there is.
Around 1980 when I was working for a small custom/tolling chemical company, there was a fuel additive outfit in Fort Worth called Octane Boost Corporation who were looking for a domestic producer of MMT for their business, because with lead having been phased out, the only remaining MMT producer was in the UK.
I had wanted to produce it myself, and started a company called Volunteer Chemical, but didn't have the time or money to build my own plant, so I brokered it to a plant where I had worked at before. They screwed me out of most of my commissions and then blew up their plant with a hydrogen explosion (H2 is a byproduct in the MMT process).
