Well like your race gas, I like the methonal for the fact that we usually have at least a drum for the car, but if you are trying to use a smoke system, might not work, lot less heat. I really liked that 10 percent methonal that I mixed up, stays mixed, and I havent had any performance problems from the fuel, mixed almost 3 months ago, using the last of it come monday. I dont' know how it will work out with the gx31 that you have, but moving the timing I would bet on, and if you did that the meth mix would work.
That car sounds like a beast!

What do the intake and exhaust ports look like in that 4 cycle?
What kind of exhaust are you running on it? SS