Snowman, you do not need to have a goal of making a lot of power by using a methanol injection system.
I am suggesting for you to run cheap gas all the time (like you mostly want to in order to save some $$$$), 87 octane & you can go with higher boost w/87 octane & using a methanol injection system.
Not exactly sure what octane you would get by using 87 octane & a meth kit installed, but it will be more octane than running straight 91 octane for sure.
After you install a intercooler system & meth injection system, I can see you running 15 psi of boost pressure pretty easy, & you said your car was crazy fast when boosting to 15 psi, correct?
I think you should keep your fuel system as simple as possible. It is a neat idea of what you are thinking about doing & people have done dual fuel systems w/success.
Believe me when I say you will be more than happy the way your car will run on 87 octane , intercooler installed & a meth kit. Have I steered you wrong so-far?
Also, I high light my words to you on my posts because I think you do not go to the links I post or sometimes actually read my posts. You dont have to, just thought you want some input. I just mean for you to pay attention if you like. If I was shouting, they would all be caps.