Jacob, there are other factors. The alky being injected into the airstream cools the air prior to reaching the intake ports. This is in addition to the fuel at the port. Quite a bit of alky is injected relative to the amount of fuel being injected. Mixed in the tank, it would not be an "addition", it would be actually "taking the place" of some of the fuel. Stick with Xylene if you want to put stuff in your tank!