I experiemented a lot with octane boosters with a prior car that was turbocharged. it was very much impacted by octane. even more so after I tweaked the ECU and cranked up boost.
running CA 91 octane, the car ran fine, but did not have maximum power. on 100 octane race fuel, or a blend of 91/100 - the car would make probably 20hp more to the ground. another guy with the same car verified this on the dyno.
i briefly tried toluene and xylene. some of this stuff you can get at lowes, home depot. the stuff is stinky, and is a major PITA to handle. you need to wear gloves as it's toxic. also, if you do get it on your hands, your skin will literally hurt like a minor sun burn. needless to say I quit using this crap.
besides, i don' tthink it helped enough to justify all the risks, hassles.
find a nice gas station near your house that stocks 100 octane unleaded race fuel. if you look hard enough you can probably find one. i managed to find a couple that sold 100 at the pumps. not cheap, but in the long run, it's so much less hassle it's not even worth considering that other stuff.
if you must try an octane booster, the best stuff I found was made by Lucas. I also found the NOS "race" brand worked. the ones that really work have MMT in it - although MMT (and xylene/toluene) are supposed to have stuff in it that is bad for fuel lines and/or catalytic converters.
on our cars - I wonder if there is really much of anything to gain with octane boosters. on a stock motor - has anyone really seen any noticeable improvement in horsepower, throttle response, etc by using higher octane fuel?
on my past car (S60R modified by
www.evolvecars.com) i could tell a difference just by blending in about 5 gallons of 100 octane into the rest of my tank of 91...using online blend charts, I figured that 93-94 octane was the sweet spot where i got the best improvement with the least amount of $$$ gas to add.
but on THAT car - it REALLY made a difference. no dyno needed. run it w/out the 100 blended in and youf elte like you were far far far slower.