I already said this in your other thread, but most of them don't really do anything. Will maybe raise your octane from 93 to 94. Even if you were to run 100 octane fuel in an otherwise stock car, you wouldn't really see any performance gains because the ECU is tuned for 91 and can't take advantage of the increased octane.
That being said, BOOSTane's website claims one can will raise the octane of 17.5 gal of 93 up to 102. If you have a custom tune that can take advantage of that, I'm sure you could expect some decent performance gains. Maybe 10-20 hp, but that's just a wild ass guess...it's also $20-30 a bottle so it better make a difference for what you're paying. The $4 bottle at walmart ain't gonna do shit.
Interestingly enough, they also have dyno plots that claim a 27hp increase with no tuning on a stock 335i. I know the DME in our cars is pretty smart and may be able to do some slight self tuning. One weird thing in their description though, is that they say "we brought the vehicle near knock on pump grade, 93 octane". I wonder how they did that? Maybe by limiting airflow to the intercooler to increase IAT? In that case, the stock tune would usually pull timing, but might not need to with higher octane fuel?
https://boostane.com/dyno-test-resul...-turbocharged/
What are you trying to get out of adding octane booster? If you want that extra 20hp, I think getting the PPK flash tune, MHD, or Dinan tune would give you that 100% of the time without having to spend $20 extra per tank