First I know all combo will differ.Looking for a parameter more or less. How much weather swing makes performance change. Example My old setup I never worried about anything less than 500' correct Alt. and/or 15 grains water. If on line I would adjust according. When running a mixture I figure to be 25% give or take if that makes big difference. I know nitro has bigger window due to AFR and should increase tuning window over straight alcohol. A rule of thumb will work here too.