It was a high pitched whine that we heard with the 14x4 and so decided to change the prop. With the 14x8 the tone changed dramatically, it was much softer. So much so that the first time I had difficulty tuning her by ear.

I have a 14x6 (though its on another model) and I will try it out over the week end, I have also flushed the carb as I said and am brewing 0% nitro fuel. So I will change one variable at a time

Ameyam