Originally posted by InitialD
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.
Add in air temp and humidity variables and Ill prove you wrong. Read back a few pages to the discussion we had on this already. Increasing nitro content only works if you have the temperature to make use of it. If the air temperature drops you can make more power from 20% than you can from 40%. Only reason Mike used 60% in Florida was because it was a real scorcher and the extra nitro became an advantage.