If you try a fuel with a different nitro % then you MUST readjust the needle settings (particularly high speed). Think of it this way, if you decided to run your lawnmower on methanol instead of gas then the carb jets have to be twice as big in area to flow enough methanol. Nitro has the same affect on methanol. The jet has to be bigger than what methanol by itself needs but it's easy for us to make the jet bigger, we just screw the needle out a bit

Actually it's good practise to retune even if you only change brands of fuel.