Originally posted by Palmaris Europe
I would personally stick with what you have. There is no major power gain from going to 40% from 30%.
You will see power gain going from 30% to 40% fuel. Else, Mike Swauger would not have used it !
Of course this accelerates wear and tear too.
Like Marcos mentioned, you just need to tune the engine right with the fuel you are going to use which means going to colder plug or adding shims under the combustion chamber.
But I agree that for weekend to weekend club racing, no point going to 40% at the expense of higher wear and tear.